clfilter: verify logic should be unfiltered

To verify a changelog obviously needs all of it. The verify logic now
ensures it works on an unfiltered repository.

mercurial/verify.py

@@ -25,6 +25,7 b' def _normpath(f):'
     return f
 
 def _verify(repo):
+    repo = repo.unfiltered()
     mflinkrevs = {}
     filelinkrevs = {}
     filenodes = {}