* posixpath.expanduser() now returns the input path unchanged if
  the HOME environment variable is not set and pwd.getpwuid() raises
  KeyError (the current user identifier doesn't exist in the password
  database).
* Add test_no_home_directory() to test_site.

* bpo-31572: Get rid of PyObject_HasAttrString() in ctypes.

* Fix error handling for _pack_.

* Don't silence errors when look up in a dict.

* Use _PyObject_LookupAttrId().

* More changes.

platform.libc_ver() now uses os.confstr('CS_GNU_LIBC_VERSION') if
available and the *executable* parameter is not set. The default
value of the libc_ver() *executable* parameter becomes None.

Quick benchmark on Fedora 29:

python3 -m perf command ./python -S -c 'import platform; platform.libc_ver()'
94.9 ms +- 4.3 ms -> 33.2 ms +- 1.4 ms: 2.86x faster (-65%)

On Travis CI, FTP tests of test_urllib2net randomly fail with "425
Security: Bad IP connecting".

test.pythoninfo now also logs TRAVIS environment variable.

Only platform._syscmd_file() uses subprocess. Move subprocess import
inside this function to reduce the number of imports at Python
startup.

Remove also warnings import which is no longer needed.

When using link time optimizations, the -flto flag is passed to
BASECFLAGS, which makes it propagate to distutils. Those flags
should be reserved for the interpreter and the stdlib extension
modules only, thus moving those flags to CFLAGS_NODIST.

Fix minor typo in test function name.

Fixes `loop.add_writer` and `loop.add_signal_handler` method documentation to correctly reference the callback parameter from method signature.


https://bugs.python.org/issue35395

Also refactor the call recording imolementation and add some notes
about its limitations.

* PyInit_time() now returns NULL if an exception is raised.
* Rename PyInit_timezone() to init_timezone(). "PyInit_" prefix is
  a special prefix for function initializing a module.
  init_timezone() doesn't initialize a module and the function is not
  exported.

If HAVE_DECL_TZNAME, PyInit_timezone() now returns -1 on error.

Use "ll" instead of the nonstandard "q".

* Add create_autospec with partial function returned in getattr

* Use self.assertFalse instead of assert

* Use different names and remove object

Replace strncpy() with memcpy() in structseq_repr() to fix the
following compiler warning:

Objects/structseq.c:187:5: warning: 'strncpy' specified bound depends on the length of the source argument [-Wstringop-overflow=]
     strncpy(pbuf, typ->tp_name, len);
     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Objects/structseq.c:185:11: note: length computed here
     len = strlen(typ->tp_name) > TYPE_MAXSIZE ? TYPE_MAXSIZE :

The function writes the terminating NUL byte later.

get_gmtoff() now returns time_t instead of int to fix the following
Visual Studio warning:

    Modules\timemodule.c(1183): warning C4244: 'return':
    conversion from 'time_t' to 'int', possible loss of data

'here' variable is no longer needed.

Modify asyncio tests to utilize the certificates from the test directory
instead of its own set, as they are the same and with each update they had
to be updated as well.

Fix an undefined behaviour in the pthread implementation of
PyThread_start_new_thread(): add a function wrapper to always return
NULL.

Add pythread_callback struct and pythread_wrapper() to thread_pthread.h.

Replace strncpy() with memcpy() in call_readline() to fix the
following warning, the NUL byte is written manually just after:

Modules/readline.c: In function ‘call_readline’:
Modules/readline.c:1303:9: warning: ‘strncpy’ output truncated before
terminating nul copying as many bytes from a string as its length
[-Wstringop-truncation]
         strncpy(p, q, n);
         ^~~~~~~~~~~~~~~~
Modules/readline.c:1279:9: note: length computed here
     n = strlen(p);
         ^~~~~~~~~

* Replace testInheritFlags() with two tests:
  testInheritFlagsBlocking() and testInheritFlagsTimeout()
  to test different default socket timeout. Moreover, the test now
  checks sock.gettimeout() rather than a functional test on recv().
* Replace time.time() with time.monotonic()
* Add socket_setdefaulttimeout() context manager to restore the
  default timeout when the test completes.
* Remove testConnect(): accept() wasn't blocking and testAccept()
  already tests non-blocking accept().
* Remove accept() functional test from testInitNonBlocking():
  already tested by testAccept()
* Rewrite testSetBlocking() with a new assert_sock_timeout() method
* Use addCleanup() and context manager to close sockets
* Replace assertTrue(x < y) with assertLess(x, y)

testAccept() and testRecv() of test_socket.NonBlockingTCPTests have a
race condition: time.sleep() is used as a weak synchronization
primitive and the tests fail randomly on slow buildbots.

Use a reliable threading.Event to fix these tests.

Other changes:

* Replace send() with sendall()
* Expect specific BlockingIOError rather than generic OSError
* Add a timeout to select() in testAccept() and testRecv()
* Use addCleanup() to close sockets
* Use assertRaises()

Fix PYTHONCOERCECLOCALE=1 environment variable: only coerce the C
locale if the LC_CTYPE locale is "C".

PyType_GetFlags() return type is unsigned long, not long.

Remove platform.popen() function, it was deprecated since Python 3.3:
use os.popen() instead.

Rename also the "Removed" section to "API and Feature Removals"
of What's New in Python 3.8.