git: remove unrequired assignment of listignored and listunknown

Caught by test-check-pyflakes.t

hgext/git/dirstate.py

@@ -129,7 +129,7 b' class gitdirstate(object):'
             return False
 
     def status(self, match, subrepos, ignored, clean, unknown):
-        listignored, listclean, listunknown = ignored, clean, unknown
+        listclean = clean
         # TODO handling of clean files - can we get that from git.status()?
         modified, added, removed, deleted, unknown, ignored, clean = (
             [],