Issue #16447: Fix potential segfault when setting __name__ on a class.
Revert changes for #13355 by request from Raymond Hettinger
Issue #17715: Add missing NULL Check to PyNumber_Long.
#17686: fix broken link in Doc/using/unix.rst.  Patch by Dan Riti.
#17571: remove broken links in datetime.py docstring.
Issue #17016: Get rid of possible pointer wraparounds and integer overflows
in the re module.  Patch by Nickolai Zeldovich.
#2118: clarify smtplib exception documentation.
Reflow paragraph.
Issue #16804: Fix 'python -S -m site' failure.

This commit fixes a bug in the 'site' module that was causing an exception
to incorrectly be thrown when running 'python -S -m site'.  The problem was
that 'USER_BASE' and 'USER_SITE' were being accessed before they were properly
initialized.  The code has been changed to use 'getuserbase' and
'getusersitepackages' instead so that the initialization always happens.
Fix pickling test in test_memoryio.

The test was closing the orginal object instead the copy. This didn't result
in visible failures because the loop range was incorrect as well.
Clarify point in name mangling doc.
Update using/mac documentation which was still on 2.5.
Clean up error messages raised by save_reduce in _pickle.
Closes #17726: small clarification in design FAQ.
Update code examples using collections.abc classes.
bind('') does not do the same as bind('localhost')
Merge heads.
Closes #13638: document PyErr_SetFromErrnoWithFilenameObject,
PyErr_SetFromWindowsErrWithFilenameObject, and
PyErr_SetExcFromWindowsErrWithFilenameObject.

Note that PyErr_SetExcFromWindowsErrWithFilenameObjectAndSomeOtherParametersSoThatTheNameGetsSoLongThatNobodyIsEverGonnaUseThisStrangeFunctionForAnything is still undocumented.
Closes #14462: allow any valid Python identifier in sre group names, as documented.
Clarify that the function *definition* creates the function and the binding in the module globals.