py3: define and use pycompat.itervalues() .itervalues() only exists on Python 2. Python 3's equivalent is .values(). But we don't want to blindly use .values() everywhere because on Python 2, it will create a list, which will have performance implications. This commit introduces pycompat.itervalues() which will call the appropriate method on the passed object. We update all callers of obj.itervalues() to pycompat.itervalues(obj) instead. With this commit, the only source tranforming remaining is for iteritems(). Victory is near... Differential Revision: https://phab.mercurial-scm.org/D7013