Otherwise when /bin/sh is dash it fails with

    t/tfault-run: 35: test: on_pagefault: unexpected operator

Otherwise, if previous test.fault failed, tfault-run fails to start, e.g.

    >>> test.fault
    $ make test.fault # MAKEFLAGS=-j1
    x86_64-linux-gnu-gcc -pthread -g -Wall -D_GNU_SOURCE -std=gnu99 -fplan9-extensions -Wno-declaration-after-statement -Wno-error=declaration-after-statement  -Iinclude -I3rdparty/ccan -I3rdparty/include   bigfile/tests/tfault.c lib/bug.c lib/utils.c 3rdparty/ccan/ccan/tap/tap.c  -o bigfile/tests/tfault.t
    t/tfault-run bigfile/tests/tfault.t faultr on_pagefault
    mkdir: cannot create directory ‘t/tfault-run.faultr’: File exists
    Makefile:186: recipe for target 'faultr.tfault' failed
    make: *** [faultr.tfault] Error 1
    rm bigfile/tests/tfault.t
    error   test.fault      0.433s  # 1t 1e 0f 0s

We are going to add C++ parts to wendelin.core soon.
Mark all current functionality with `extern "C"` as a preparatory step.

Else on-heap allocated RAM object is leaked. Fixes e.g. the following
error on ASAN:

	Direct leak of 56 byte(s) in 1 object(s) allocated from:
	    #0 0x7fc9ef390518 in calloc (/usr/lib/x86_64-linux-gnu/libasan.so.5+0xe9518)
	    #1 0x555ca792f309 in zalloc include/wendelin/utils.h:67
	    #2 0x555ca7935f9a in ram_limited_new bigfile/tests/../../t/t_utils.c:35
	    #3 0x555ca793a0ba in test_file_access_synthetic bigfile/tests/test_virtmem.c:292
	    #4 0x555ca7967bc4 in main bigfile/tests/test_virtmem.c:1121
	    #5 0x7fc9ef0e909a in __libc_start_main ../csu/libc-start.c:308

This continues 6ab95220 (t/qemu-runlinux: Issue terminal resize before
running program) and fully initializes terminal before spawning user
application.

This has practical effect to restore line wrapping for xterm, as kernel,
initially assuming it has "linux" type terminal, somehow messes xterm
settings: before the patch lines that were wider than terminal width were
not wrapped and characters in the last position were printed over each
other. After the patch printed lines are automatically wrapped and test
output is not lost.

Tput hint found here:

	https://unix.stackexchange.com/questions/105958

	0: ERROR+ on boot/run
	1: INFO+  on      run
	2: INFO+  on boot/run
	3: DEBUG+ on boot/run

It is convenient not to see large kernel boot log on every test run. "1"
(single -v) is also convenient: one can skip the boot log but still see
details of what is going on when test workload is run. -vv and -vvv are
there to see full picture.

bpf is needed for tools like bpftrace.
fusectl is needed to observe things like /sys/fs/fuse/connections/X/waiting.

Else program inside sees default terminal settings to be 80x25,
while after the patch it sees correct settings.

Still something is not completely right with terminal settings, as e.g.
vsplit is not working correctly in vim (vertical ruler is not straight).

Graphics mode runs in another window with its own terminal emulation,
so propagating e.g. TERM=xterm to where it is emulated as TERM=linux is
not correct.

Continuing 76d8f76d (Script to run compiled linux kernel with root fs
mounted from host) update the script to run/debug linux inside QEMU:

- teach it to run specified program + args, instead of hardcoded /bin/sh;
- before tailing to user program, builtin init mounts /proc, /sys, ...
  inside - previously it was /proc, /sys from host seen on those
  mountpoints and it was very misleading - e.g. ps was showing processes
  from host, not inside, etc.
- builtin init also cares to run specified program with the same current
  directory that was current on host, and environments such as $HOME,
  $PATH, $TERM, ... are also propagated.
- allow to optionally run QEMU with graphics, instead of stdout only;
- increase available RAM from 128M to 512M (with 128M running py.test
  inside is failing with fork: not enough memory).

This updated version was useful to debug WCFS(*) & FUSE issues by running

	kirr@deco:~/src/wendelin/wendelin.core/wcfs$ ../t/qemu-runlinux ~/src/linux/linux/arch/x86_64/boot/bzImage py.test -vsx -k test_wcfs

See https://marc.info/?l=linux-fsdevel&m=155000277921155&w=2 for details.

(*) WCFS is still being draft and worked on t branch.

Currently fails with:

/home/kirr/src/wendelin/wendelin.core/lib/xnumpy.py in restructure(arr, dtype)
     82     print 'stridev:', stridev
     83     #return np.ndarray.__new__(type(arr), shape, dtype, buffer(arr), 0, stridev)
---> 84     return np.ndarray(shape, dtype, buffer(arr), 0, stridev)

TypeError: expected a single-segment buffer object

So that it can be available to everyone and in particular B & friends to
be available from introduced importable golang.testing package. The move
itself:

	pygolang@9bf03d9c

While moving the code was restructured / improved a bit and py.bench
interface reworked to mimic `go test -bench` in defaults.

Benchmark the time it takes for virtmem to handle pagefault with noop
loadblk for loadblk both implemented in C and in Python.

On my computer it is:

	name          µs/op
	PagefaultC    269 ± 0%
	pagefault_py  291 ± 0%

Quite a big time in other words.

It turned out to be mostly spent in fallocate'ing pages on tmpfs from
/dev/shm. Part of the above 269 µs/op is taken by freeing (reclaiming)
pages back when benchmarking work size exceed /dev/shm size, and part to
allocating.

If I limit the work size (via npage in benchmem.c) to be less than whole
/dev/shm it starts to be ~ 170 µs/op and with additional tracing it
shows as something like this:

    	.. on_pagefault_start   0.954 µs
    	.. vma_on_pagefault_pre 0.954 µs
    	.. ramh_alloc_page_pre  0.954 µs
    	.. ramh_alloc_page      169.992 µs
    	.. vma_on_pagefault     172.853 µs
    	.. vma_on_pagefault_pre 172.853 µs
    	.. vma_on_pagefault     174.046 µs
    	.. on_pagefault_end     174.046 µs
    	.. whole:               171.900 µs

so almost all time is spent in ramh_alloc_page which is doing the fallocate:

	https://lab.nexedi.com/nexedi/wendelin.core/blob/f11386a4/bigfile/ram_shmfs.c#L125

Simple benchmark[1] confirmed it is indeed the case for fallocate(tmpfs) to be
relatively slow[2] (and that for recent kernels it regressed somewhat
compared to Linux 3.16). Profile flamegraph for that benchmark[3] shows
internal loading of shmem_fallocate which for 1 hardware page is not
that too slow (e.g. <1µs) but when a request comes for a region
internally performs it page by page and so accumulates that ~ 170µs for 2M.

I've tried to briefly rerun the benchmark with huge pages activated on /dev/shm via

	mount /dev/shm -o huge=always,remount

as both regular user and as root but it was executing several times
slower. Probably something to investigate more later.

[1] https://lab.nexedi.com/kirr/misc/blob/4f84a06e/tmpfs/t_fallocate.c
[2] https://lab.nexedi.com/kirr/misc/blob/4f84a06e/tmpfs/1.txt
[3] https://lab.nexedi.com/kirr/misc/raw/4f84a06e/tmpfs/fallocate-2M-nohuge.svg

Rework py.bench output to match output of Go benchmarking[1] so that go
tools like benchstat & friends could be used to analyze and compare the
timings.

Before patch:

============================= test session starts ==============================
platform linux2 -- Python 2.7.14, pytest-3.3.2.dev2+g88f2cc9b.d20171206, py-1.5.2, pluggy-0.6.0
rootdir: /home/kirr/src/wendelin/wendelin.core, inifile:
collected 11 items

pymod: bigfile/tests/bench_0virtmem.py
bench_file_mmapread_hole	0.21  (0.39 0.22 0.21)
bench_file_read_hole    	0.24  (0.24 0.24 0.24)
bench_file_readbig_hole 	0.30  (0.30 0.31 0.31)
bench_bigf_read_hole    	0.44  (0.44 0.45 0.44)
bench_file_mmapwrite0   	0.13  (0.13 0.13 0.13)
bench_file_write55      	0.08  (0.08 0.08 0.08)
bench_bigf_writeff      	0.47  (0.47 0.48 0.47)
bench_file_mmapread     	0.22  (0.22 0.22 0.22)
bench_file_read         	0.25  (0.25 0.25 0.26)
bench_file_readbig      	0.31  (0.31 0.31 0.31)
bench_bigf_read         	0.44  (0.45 0.44 0.44)

========================== 11 passed in 12.92 seconds ==========================

After patch:

============================= test session starts ==============================
platform linux2 -- Python 2.7.14, pytest-3.3.2.dev2+g88f2cc9b.d20171206, py-1.5.2, pluggy-0.6.0
rootdir: /home/kirr/src/wendelin/wendelin.core, inifile:
collected 11 items

pymod: bigfile/tests/bench_0virtmem.py
Benchmarkfile_mmapread_hole	1	385839.939 µs/op
Benchmarkfile_mmapread_hole	1	219214.916 µs/op
Benchmarkfile_mmapread_hole	1	210209.131 µs/op
Benchmarkfile_read_hole    	1	238974.094 µs/op
Benchmarkfile_read_hole    	1	237294.197 µs/op
Benchmarkfile_read_hole    	1	238043.070 µs/op
Benchmarkfile_readbig_hole 	1	301330.090 µs/op
Benchmarkfile_readbig_hole 	1	301767.111 µs/op
Benchmarkfile_readbig_hole 	1	301135.063 µs/op
Benchmarkbigf_read_hole    	1	434718.132 µs/op
Benchmarkbigf_read_hole    	1	435019.970 µs/op
Benchmarkbigf_read_hole    	1	434729.099 µs/op
Benchmarkfile_mmapwrite0   	1	126471.996 µs/op
Benchmarkfile_mmapwrite0   	1	125886.917 µs/op
Benchmarkfile_mmapwrite0   	1	125730.038 µs/op
Benchmarkfile_write55      	1	86760.044 µs/op
Benchmarkfile_write55      	1	87507.010 µs/op
Benchmarkfile_write55      	1	87735.891 µs/op
Benchmarkbigf_writeff      	1	448369.980 µs/op
Benchmarkbigf_writeff      	1	448238.850 µs/op
Benchmarkbigf_writeff      	1	447322.845 µs/op
Benchmarkfile_mmapread     	1	207049.131 µs/op
Benchmarkfile_mmapread     	1	207813.978 µs/op
Benchmarkfile_mmapread     	1	210857.868 µs/op
Benchmarkfile_read         	1	238364.935 µs/op
Benchmarkfile_read         	1	236908.913 µs/op
Benchmarkfile_read         	1	238602.161 µs/op
Benchmarkfile_readbig      	1	303429.842 µs/op
Benchmarkfile_readbig      	1	302191.973 µs/op
Benchmarkfile_readbig      	1	304115.057 µs/op
Benchmarkbigf_read         	1	435079.098 µs/op
Benchmarkbigf_read         	1	434193.850 µs/op
Benchmarkbigf_read         	1	434813.976 µs/op

========================== 11 passed in 12.54 seconds ==========================

benchstat of new output:

	name                µs/op
	file_mmapread_hole   272k ±42%
	file_read_hole       238k ± 0%
	file_readbig_hole    301k ± 0%
	bigf_read_hole       435k ± 0%
	file_mmapwrite0      126k ± 0%
	file_write55        87.3k ± 1%
	bigf_writeff         448k ± 0%
	file_mmapread        209k ± 1%
	file_read            238k ± 0%
	file_readbig         303k ± 0%
	bigf_read            435k ± 0%

--------

Not only the output format is reworked here, but also b fixture is added
to BenchPlugin so that functions which accept it as arg, can run the
benchmark b.N times, can stop/restart timer etc - similar to
https://golang.org/pkg/testing/#B . If a bench_* func does not accept b,
B is still created, but b.N is assumed to be always 1.

The first benchmark which actually uses b will come in the next patch.

[1] https://github.com/golang/proposal/blob/master/design/14313-benchmark-format.md

For several benchmarks in a python module instead of always printing
whole benchmark function path (nodeid in pytest speak), first print

	pymod: modulename

header, and then only function names.

Before patch:

============================= test session starts ==============================
platform linux2 -- Python 2.7.14, pytest-3.3.0, py-1.5.2, pluggy-0.6.0
rootdir: /home/kirr/src/wendelin/wendelin.core, inifile:
collected 14 items

bigfile/tests/bench_0virtmem.py::bench_file_mmapread_hole 	0.22  (0.39 0.22 0.22)
bigfile/tests/bench_0virtmem.py::bench_file_read_hole    	0.24  (0.24 0.24 0.24)
bigfile/tests/bench_0virtmem.py::bench_file_readbig_hole 	0.30  (0.30 0.30 0.30)
bigfile/tests/bench_0virtmem.py::bench_bigf_read_hole    	0.43  (0.43 0.43 0.43)
bigfile/tests/bench_0virtmem.py::bench_file_mmapwrite0   	0.12  (0.13 0.12 0.13)
bigfile/tests/bench_0virtmem.py::bench_file_write55      	0.08  (0.08 0.08 0.08)
bigfile/tests/bench_0virtmem.py::bench_bigf_writeff      	0.45  (0.45 0.45 0.45)
bigfile/tests/bench_0virtmem.py::bench_file_mmapread     	0.21  (0.21 0.21 0.22)
bigfile/tests/bench_0virtmem.py::bench_file_read         	0.23  (0.23 0.24 0.24)
bigfile/tests/bench_0virtmem.py::bench_file_readbig      	0.30  (0.30 0.30 0.30)
bigfile/tests/bench_0virtmem.py::bench_bigf_read         	0.43  (0.44 0.43 0.44)
bigfile/tests/bench_1filezodb.py::bench_bigz_readhole    	0.42  (0.42 0.43 0.43)
bigfile/tests/bench_1filezodb.py::bench_bigz_writeff     	0.84  (0.84 1.25 1.25)
bigfile/tests/bench_1filezodb.py::bench_bigz_read        	0.60  (0.64 0.60 0.60)
========================== 14 passed in 21.78 seconds ==========================

After patch:

============================= test session starts ==============================
platform linux2 -- Python 2.7.14, pytest-3.3.0, py-1.5.2, pluggy-0.6.0
rootdir: /home/kirr/src/wendelin/wendelin.core, inifile:
collected 14 items

pymod: bigfile/tests/bench_0virtmem.py
bench_file_mmapread_hole	0.21  (0.39 0.22 0.21)
bench_file_read_hole    	0.24  (0.24 0.24 0.24)
bench_file_readbig_hole 	0.30  (0.30 0.30 0.30)
bench_bigf_read_hole    	0.43  (0.43 0.43 0.43)
bench_file_mmapwrite0   	0.12  (0.13 0.12 0.13)
bench_file_write55      	0.08  (0.08 0.08 0.08)
bench_bigf_writeff      	0.45  (0.52 0.51 0.45)
bench_file_mmapread     	0.21  (0.21 0.21 0.21)
bench_file_read         	0.24  (0.24 0.24 0.24)
bench_file_readbig      	0.30  (0.30 0.30 0.30)
bench_bigf_read         	0.43  (0.43 0.43 0.43)

pymod: bigfile/tests/bench_1filezodb.py
bench_bigz_readhole     	0.43  (0.43 0.43 0.43)
bench_bigz_writeff      	0.83  (0.83 1.20 1.21)
bench_bigz_read         	0.60  (0.65 0.60 0.60)

========================== 14 passed in 21.80 seconds ==========================

The `key: value` header is compatible with Go benchmark format[1] and
further we'll be trying to teach py.bench to output results in that
format so that Go benchmarking tools like benchstat and perf.golang.org
could be used for free.

[1] https://github.com/golang/proposal/blob/master/design/14313-benchmark-format.md

Upstream pytest changed TerminalReporter._locationline() signature from

	def _locationline(self, collect_fspath, fspath, lineno, domain):

to

	def _locationline(self, nodeid, fspath, lineno, domain):

https://github.com/pytest-dev/pytest/commit/d73e6899 .

This way without adjusting py.bench was reporting just filenames instead
of benchmark names, e.g. this way:

(z-dev) kirr@deco:~/src/wendelin/wendelin.core$ ./t/py.bench bigfile/tests/bench_0virtmem.py
=============================================================== test session starts ===============================================================
platform linux2 -- Python 2.7.14, pytest-3.3.0, py-1.5.2, pluggy-0.6.0
rootdir: /home/kirr/src/wendelin/wendelin.core, inifile:
collected 11 items

bigfile/tests/bench_0virtmem.py                                 0.21  (0.38 0.22 0.21)
bigfile/tests/bench_0virtmem.py                                 0.23  (0.23 0.24 0.23)
bigfile/tests/bench_0virtmem.py                                 0.30  (0.30 0.30 0.30)
bigfile/tests/bench_0virtmem.py                                 0.43  (0.43 0.43 0.43)
bigfile/tests/bench_0virtmem.py                                 0.12  (0.12 0.12 0.12)
bigfile/tests/bench_0virtmem.py                                 0.08  (0.08 0.08 0.08)
bigfile/tests/bench_0virtmem.py                                 0.44  (0.44 0.44 0.44)
bigfile/tests/bench_0virtmem.py                                 0.20  (0.20 0.20 0.21)
bigfile/tests/bench_0virtmem.py                                 0.24  (0.24 0.24 0.24)
bigfile/tests/bench_0virtmem.py                                 0.30  (0.30 0.30 0.30)
bigfile/tests/bench_0virtmem.py                                 0.43  (0.43 0.43 0.43)

=========================================================== 11 passed in 12.39 seconds ============================================================

Fix it.

In pytest3 pytest_runtest_call hook is always run as multicall and there
is no way to control to disable it and force e.g. 'firstresult'
behaviour. This way call.result in pytest_runtest_makereport is always a
list of returned results, not the first result itself.

Adjust the code in pytest_runtest_makereport to emulate 'firstresult'
behaviour manually.

Without the patch with recent pytest py.bench was crashing like this:

---- 8< ----
(z-dev) kirr@link:~/src/wendelin/wendelin.core$ make bench
python setup.py ll_build_ext --inplace
running ll_build_ext
copying build/lib.linux-x86_64-2.7/wendelin/bigfile/_bigfile.so -> bigfile
python t/py.bench --ignore=3rdparty --ignore=build --ignore=t
============================================================= test session starts ==============================================================
platform linux2 -- Python 2.7.14, pytest-3.3.0, py-1.5.2, pluggy-0.6.0
rootdir: /home/kirr/src/wendelin/wendelin.core, inifile:
collected 14 items

bigfile/tests/bench_0virtmem.py                          	INTERNALERROR> Traceback (most recent call last):
INTERNALERROR>   File "/home/kirr/src/wendelin/venv/z-dev/local/lib/python2.7/site-packages/_pytest/main.py", line 103, in wrap_session
INTERNALERROR>     session.exitstatus = doit(config, session) or 0
INTERNALERROR>   File "/home/kirr/src/wendelin/venv/z-dev/local/lib/python2.7/site-packages/_pytest/main.py", line 141, in _main
INTERNALERROR>     config.hook.pytest_runtestloop(session=session)
INTERNALERROR>   File "/home/kirr/src/wendelin/venv/z-dev/local/lib/python2.7/site-packages/pluggy/__init__.py", line 617, in __call__
INTERNALERROR>     return self._hookexec(self, self._nonwrappers + self._wrappers, kwargs)
INTERNALERROR>   File "/home/kirr/src/wendelin/venv/z-dev/local/lib/python2.7/site-packages/pluggy/__init__.py", line 222, in _hookexec
INTERNALERROR>     return self._inner_hookexec(hook, methods, kwargs)
INTERNALERROR>   File "/home/kirr/src/wendelin/venv/z-dev/local/lib/python2.7/site-packages/pluggy/__init__.py", line 216, in <lambda>
INTERNALERROR>     firstresult=hook.spec_opts.get('firstresult'),
INTERNALERROR>   File "/home/kirr/src/wendelin/venv/z-dev/local/lib/python2.7/site-packages/pluggy/callers.py", line 201, in _multicall
INTERNALERROR>     return outcome.get_result()
INTERNALERROR>   File "/home/kirr/src/wendelin/venv/z-dev/local/lib/python2.7/site-packages/pluggy/callers.py", line 77, in get_result
INTERNALERROR>     _reraise(*ex)  # noqa
INTERNALERROR>   File "/home/kirr/src/wendelin/venv/z-dev/local/lib/python2.7/site-packages/pluggy/callers.py", line 180, in _multicall
INTERNALERROR>     res = hook_impl.function(*args)
INTERNALERROR>   File "/home/kirr/src/wendelin/venv/z-dev/local/lib/python2.7/site-packages/_pytest/main.py", line 164, in pytest_runtestloop
INTERNALERROR>     item.config.hook.pytest_runtest_protocol(item=item, nextitem=nextitem)
INTERNALERROR>   File "/home/kirr/src/wendelin/venv/z-dev/local/lib/python2.7/site-packages/pluggy/__init__.py", line 617, in __call__
INTERNALERROR>     return self._hookexec(self, self._nonwrappers + self._wrappers, kwargs)
INTERNALERROR>   File "/home/kirr/src/wendelin/venv/z-dev/local/lib/python2.7/site-packages/pluggy/__init__.py", line 222, in _hookexec
INTERNALERROR>     return self._inner_hookexec(hook, methods, kwargs)
INTERNALERROR>   File "/home/kirr/src/wendelin/venv/z-dev/local/lib/python2.7/site-packages/pluggy/__init__.py", line 216, in <lambda>
INTERNALERROR>     firstresult=hook.spec_opts.get('firstresult'),
INTERNALERROR>   File "/home/kirr/src/wendelin/venv/z-dev/local/lib/python2.7/site-packages/pluggy/callers.py", line 201, in _multicall
INTERNALERROR>     return outcome.get_result()
INTERNALERROR>   File "/home/kirr/src/wendelin/venv/z-dev/local/lib/python2.7/site-packages/pluggy/callers.py", line 77, in get_result
INTERNALERROR>     _reraise(*ex)  # noqa
INTERNALERROR>   File "/home/kirr/src/wendelin/venv/z-dev/local/lib/python2.7/site-packages/pluggy/callers.py", line 180, in _multicall
INTERNALERROR>     res = hook_impl.function(*args)
INTERNALERROR>   File "/home/kirr/src/wendelin/venv/z-dev/local/lib/python2.7/site-packages/_pytest/runner.py", line 63, in pytest_runtest_protocol
INTERNALERROR>     runtestprotocol(item, nextitem=nextitem)
INTERNALERROR>   File "/home/kirr/src/wendelin/venv/z-dev/local/lib/python2.7/site-packages/_pytest/runner.py", line 77, in runtestprotocol
INTERNALERROR>     reports.append(call_and_report(item, "call", log))
INTERNALERROR>   File "/home/kirr/src/wendelin/venv/z-dev/local/lib/python2.7/site-packages/_pytest/runner.py", line 161, in call_and_report
INTERNALERROR>     hook.pytest_runtest_logreport(report=report)
INTERNALERROR>   File "/home/kirr/src/wendelin/venv/z-dev/local/lib/python2.7/site-packages/pluggy/__init__.py", line 617, in __call__
INTERNALERROR>     return self._hookexec(self, self._nonwrappers + self._wrappers, kwargs)
INTERNALERROR>   File "/home/kirr/src/wendelin/venv/z-dev/local/lib/python2.7/site-packages/pluggy/__init__.py", line 222, in _hookexec
INTERNALERROR>     return self._inner_hookexec(hook, methods, kwargs)
INTERNALERROR>   File "/home/kirr/src/wendelin/venv/z-dev/local/lib/python2.7/site-packages/pluggy/__init__.py", line 216, in <lambda>
INTERNALERROR>     firstresult=hook.spec_opts.get('firstresult'),
INTERNALERROR>   File "/home/kirr/src/wendelin/venv/z-dev/local/lib/python2.7/site-packages/pluggy/callers.py", line 201, in _multicall
INTERNALERROR>     return outcome.get_result()
INTERNALERROR>   File "/home/kirr/src/wendelin/venv/z-dev/local/lib/python2.7/site-packages/pluggy/callers.py", line 77, in get_result
INTERNALERROR>     _reraise(*ex)  # noqa
INTERNALERROR>   File "/home/kirr/src/wendelin/venv/z-dev/local/lib/python2.7/site-packages/pluggy/callers.py", line 180, in _multicall
INTERNALERROR>     res = hook_impl.function(*args)
INTERNALERROR>   File "t/py.bench", line 165, in pytest_runtest_logreport
INTERNALERROR>     self._tw.write('%.2f' % min(report.bench_times))
INTERNALERROR> TypeError: float argument required, not list

If py.test machinery access any of the keys we change before we tweak
them - their values will be put to config._inicache and our tweaking
won't essentially have the effect.

It used to be working without explicit cache invalidation with older
pytests, but as of e.g. py.test 3.2.1 it does not work without explicit
cache clearing because e.g. 'python_files' is somehow accessed before
and is set to std 'test_*.py' + friends in the cache and this way
py.bench then does not collect benchmarks from bench_*.py files.

Fix it by making sure inicache is invalidated after our inicfg tweak.

Relicense to GPLv3+ with wide exception for all Free Software / Open Source projects + Business options.

Nexedi stack is licensed under Free Software licenses with various exceptions
that cover three business cases:

- Free Software
- Proprietary Software
- Rebranding

As long as one intends to develop Free Software based on Nexedi stack, no
license cost is involved. Developing proprietary software based on Nexedi stack
may require a proprietary exception license. Rebranding Nexedi stack is
prohibited unless rebranding license is acquired.

Through this licensing approach, Nexedi expects to encourage Free Software
development without restrictions and at the same time create a framework for
proprietary software to contribute to the long term sustainability of the
Nexedi stack.

Please see https://www.nexedi.com/licensing for details, rationale and options.

No one was freeing RAMH structure itself, and thus ASAN reports e.g.:

==15935==ERROR: LeakSanitizer: detected memory leaks

Direct leak of 32 byte(s) in 1 object(s) allocated from:
    #0 0x7f29c89f1001 in __interceptor_calloc (/usr/lib/x86_64-linux-gnu/libasan.so.2+0x94001)
    #1 0x401da1 in zalloc include/wendelin/utils.h:65
    #2 0x408128 in shmfs_ramh_open bigfile/tests/../ram_shmfs.c:202
    #3 0x407611 in ramh_open bigfile/tests/../ram.c:81
    #4 0x402560 in fileh_open bigfile/tests/../virtmem.c:131
    #5 0x427ca1 in test_pagefault_savestate bigfile/tests/test_virtmem.c:1022
    #6 0x4281ba in main bigfile/tests/test_virtmem.c:1061
    #7 0x7f29c83b8b44 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x21b44)

NOTE similar leak remains open in ram_close(), but it is a bit involved
to fix and the effort will be removed anyway after we switch to kernel
virtual memory manager. Besides ramh are opened and closed all the time
and ram only once.