Issue #16447: Fix potential segfault when setting __name__ on a class.
Issue #16447: Merge fix from 3.3.
Issue #17643: Add __callback__ attribute to weakref.ref.
Revert changes for #13355 by request from Raymond Hettinger
Revert changes for #13355 by request from Raymond Hettinger
Fix incorrect indentation on 'versionadded' for weakref.ref.__callback__.
Merge heads.
Issue #17713: Test temporarily skipped while failure investigated.
Issue #17715: Add missing NULL Check to PyNumber_Long.
Issue #17715: Merge fix from 3.3.
#17686: fix broken link in Doc/using/unix.rst.  Patch by Dan Riti.
#17686: merge with 3.3.
#17571: remove broken links in datetime.py docstring.
#17571: merge with 3.3.
Issue #17016: Get rid of possible pointer wraparounds and integer overflows
in the re module.  Patch by Nickolai Zeldovich.
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.
Merge #2118: clarify smtplib exception documentation.
#2118: Make SMTPException a subclass of IOError.

Initial patch by Ned Jackson Lovely.