Clean up circular references in the Weak*Dictionary classes; this avoids depending on the cycle detector code in the library implementation. This is a *slightly* different patch than SF patch #417795, but takes the same approach.  (This version avoids calling the __len__() method of the dict in the remove() functions.) This closes SF patch #417795.
Clean up circular references in the Weak*Dictionary classes; this avoids
depending on the cycle detector code in the library implementation.
This is a *slightly* different patch than SF patch #417795, but takes
the same approach.  (This version avoids calling the __len__() method of
the dict in the remove() functions.)
This closes SF patch #417795.

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