sys.path has an unwritable __pycache__ directory.

This typically comes up when someone runs the test suite from an
administrative install of Python on Windows where the user does not
have write permissions to the stdlib's directory.

Thanks to Zachary Ware and Matthias Klose for reporting bugs related
to this issue.
(grafted from 34bbd537b3e688dfbb6498e9083445a6a72fc4b1)

Also add to comment in the C code.

This reuses existing code to hopefully make the new test_input_no_stdout_
fileno() test work. It is hanging Free BSD 9 and OS X Tiger buildbots, and I
don't know why.

Also factored out some test cases into a new PtyTests class.

Patch by Henrik Heimbuerger and Bar Harel.

Also change glossary heading from view

Made test_tokenize discoverable.

Initial patch from Xiang Zhang. Also fix out-of-date _url_collapse_path() doc
string.

Patch from Xiang Zhang.

curious users.  The previous user content is now in the IDLE doc and is
redundant.  IDLE now means 'Integrated Development and Learning Environment'.

Custom Highlighting. Original patch by Mark Roseman.

Patch by Johannes Niediek.

1. Non-ASCII bytes were accepted after shift sequence.
2. A low surrogate could be emitted in case of error in high surrogate.

longer formatted twice.

getentropy() is blocking, whereas os.urandom() should not block. getentropy()
is supported since Solaris 11.3.

sys.gettrace() when the test is executed, not when the module is loaded.

sys.settrace() may be after after the test is loaded.

Restore also errno value before calling PyErr_SetFromErrno().