add private method to enum to support replacing global constants with Enum members:
- search for candidate constants via supplied filter
- create new enum class and members
- insert enum class and replace constants with members via supplied module name
- replace __reduce_ex__ with function that returns member name, so previous Python versions can unpickle
modify IntEnum classes to use new method

Issue #22903: The fake test case created by unittest.loader when it fails importing a test module is now picklable.

Use a Python source file (linecache.__file__) instead of /etc/passwd.

Modify also linecache docstrings to clarify the linecache is written to cache
Python source files, not any text files.

source files, even if "it works" with other text files encoded to UTF-8.

PyMarshal_ReadShortFromFile() can fail.

Patch by Thomas Kluyver.

The current documentation only mentions heap[0] as the smallest element in the
beginning, and not in any of the methods' docs. There's no method to access the
minimal element without popping it, and the documentation of nsmallest is
confusing because it may suggest that min() is the way to go for n==1.

Patch by Håkan Lövdahl.

Patch by Demian Brecht.

handle exceptions raised by an iterator.  Patch by Alon Diamant and Davin
Potts.

Patch by Lars Buitinck.

Patch by Mike Short.

Fixed 2 to 3 porting bug in pynche.ColorDB.

Patch by Mark Lawrence.

Original patch by Demian Brecht.

imp.reload().  Patch by Thomas Kluyver.

Replace "running" with "not started" and don't show the pid if the subprocess
didn't start yet.

Also, document SystemExit.code attribute explicitly.