Fix bug in interpretation of the "callback" argument in the constructors for weakref ref and proxy objects; None was not being treated as identical to NULL, though it was documented as equivalent.
Fix bug in interpretation of the "callback" argument in the constructors for
weakref ref and proxy objects; None was not being treated as identical to
NULL, though it was documented as equivalent.

sk-/python2.7-type-annotator,sk-/python2.7-type-annotator,sk-/python2.7-type-annotator