Patch by Claudiu Popa.

Patch by Diana Clarke.

redirect.

PyObject_Calloc(), _PyObject_GC_Calloc(). bytes(int) and bytearray(int) are now
using ``calloc()`` instead of ``malloc()`` for large objects which is faster
and use less memory (until the bytearray buffer is filled with data).

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).

Issue #21377: PyBytes_Concat() now tries to concatenate in-place when the first argument has a reference count of 1.
Patch by Nikolaus Rath.

in the root of the source tree, which passes all arguments through
to the most recently built interpreter.

Decimal.quantize() method in the Python version.  It had never been
present in the C version.

Patch by Lukas Vacek.

supported by Doc/Makefile, as well as a bit of modernization,
cleanup, and notes about the difference between Unix and Windows.

Issue #21321: itertools.islice() now releases the reference to the source iterator when the slice is exhausted.

Patch by Anton Afanasyev.