Issue #13204: Calling sys.flags.__new__ would crash the interpreter, now it raises a TypeError.
Issue #9815: assertRaises now tries to clear references to local variables in the exception's traceback.
Issue #9307: document the various Py_TPFLAGS_*_SUBCLASS flags.  Patch by Yury V. Zaytsev.
Issue #21026: Augment site doc based on experiments. Patch by Carol Willing.
Closes 21048: Index 'as' in import and with statements.
Issue #21055: Index (augmented) assignment symbols.
Issue #21321: itertools.islice() now releases the reference to the source iterator when the slice is exhausted.

Patch by Anton Afanasyev.
Issue #17386: List the 'htmlview' target in the Doc/Makefile help output.
Issue #17386: Update Doc/README.txt to list all targets
supported by Doc/Makefile, as well as a bit of modernization,
cleanup, and notes about the difference between Unix and Windows.
Issue #17386: Expand Doc/make.bat to be much more similar to Doc/Makefile
Closes issue #21316: mark test_devpoll to be meaningfull only for Solaris
Issue #21374: Fix pickling of DecimalTuple.
Document the subprocess Popen.args attribute (issue21353)
Document the subprocess Popen.args attribute (issue21353)
Update to 1.0.1g
Issue #18604: Consolidated checks for GUI availability.

test_support._is_gui_available is now defined the same way on every
platform, and now includes the Windows-specific check that had been in the
Windows version of _is_gui_available and the OSX-specific check that was
in tkinter.test.support.check_tk_availability.  Also, every platform
checks whether Tk can be instantiated (if the platform-specific checks
passed).