commit: avoid match.files() in conditions

See 9789b4a7c595 (match: introduce boolean prefix() method,
2014-10-28) for reasons to avoid match.files() in conditions.

mercurial/localrepo.py

@@ -1444,7 +1444,7 b' class localrepository(object):'
                     status.removed.insert(0, '.hgsubstate')
 
             # make sure all explicit patterns are matched
-            if not force and match.files():
+            if not force and (match.isexact() or match.prefix()):
                 matched = set(status.modified + status.added + status.removed)
 
                 for f in match.files():