fastannotate: drop unused local variable assignments

Flagged by PyCharm.

Differential Revision: https://phab.mercurial-scm.org/D7757

hgext/fastannotate/support.py

@@ -74,7 +74,6 b' def _doannotate(fctx, follow=True, diffo'
     may raise Exception, and always return line numbers.
     """
     master = _getmaster(fctx)
-    annotated = contents = None
 
     with context.fctxannotatecontext(fctx, follow, diffopts) as ac:
         try: