Problem:    PyEval_InitThreads() is deprecated in Python 3.9.
Solution:   Do not call PyEval_InitThreads in Python 3.9 and later. (Ken
            Takata, closes #7113)  Avoid warnings for functions.

Problem:    MS-Windows: Python3 issue with stdin.
Solution:   Check if stdin is readable. (Ken Takata, closes #7106)

Problem:    MS-Windows with Python: Vim freezes after import command.
Solution:   Use either "NUL" or "CONIN$" when reopening stdin. (Yasuhiro
            Matsumoto, closes #7083)

Problem:    MS-Windows with Python: crash when executed from Vifm.
Solution:   Use NUL instead of CONIN. (Ken Takata, closes #7061, closes #7053)

Problem:    MS-Windows: crash with Python 3.5 when stdin is redirected.
Solution:   Reconnect stdin. (Yasuhiro Matsumoto, Ken Takata, closes #6641)

Problem:    Linker errors when building with dynamic Python 3.9.
Solution:   Add #defined items. (closes #6461)

Problem:    Not enough testing for Python.
Solution:   Add more tests.  Fix uncovered problems. (Yegappan Lakshmanan,
            closes #6392)

Problem:    Unloading shared libraries on exit has no purpose.
Solution:   Do not unload shared libraries on exit.

Problem:    Python 3.9 does not define _Py_DEC_REFTOTAL. (Zdenek Dohnal)
Solution:   Remove it, it was only for debugging.

Problem:    File missing in distribution, comments outdated.
Solution:   Correct path of README file.  Update comments.