Update docs about tp_richcompare
Merge 3.4
Issue #21151: Fixed a segfault in the winreg module.

When ``None`` was passed as a ``REG_BINARY`` value to SetValueEx,
PyMem_DEL was called on an uninitialized buffer.  Patch by John Ehresman.

(Also an incidental typo fix in a comment in test_winreg)
Closes #21151: Merge with 3.4
#15014: Add 'auth' command to implement auth mechanisms and use it in login.

Patch by Milan Oberkirch.