scmutil: add assertions to help pytype

Differential Revision: https://phab.mercurial-scm.org/D7456

mercurial/scmutil.py

@@ -1917,6 +1917,7 b' def registersummarycallback(repo, otr, t'
         def wrapped(tr):
             repo = reporef()
             if filtername:
+                assert repo is not None  # help pytype
                 repo = repo.filtered(filtername)
             func(repo, tr)
 
@@ -1936,6 +1937,7 b' def registersummarycallback(repo, otr, t'
             if cgheads:
                 htext = _(b" (%+d heads)") % cgheads
             msg = _(b"added %d changesets with %d changes to %d files%s\n")
+            assert repo is not None  # help pytype
             repo.ui.status(msg % (cgchangesets, cgrevisions, cgfiles, htext))
 
     if txmatch(_reportobsoletedsource):