narrow: only walk files within narrowspec also for committed revisions

Narrow has been walking only paths matching the narrowspec when
walking the working copy. We have not done the same filtering when
walking committed revisions (e.g. "hg files -r "), which seems a
little odd. Let's make it consistent.

Differential Revision: https://phab.mercurial-scm.org/D4898

mercurial/context.py

@@ -542,7 +542,7 b' class changectx(basectx):'
                 return
             match.bad(fn, _('no such file in rev %s') % self)
 
-        m = matchmod.badmatch(match, bad)
+        m = matchmod.badmatch(self._repo.narrowmatch(match), bad)
         return self._manifest.walk(m)
 
     def matches(self, match):
@@ -1168,7 +1168,7 b' class committablectx(basectx):'
 
     def walk(self, match):
         '''Generates matching file names.'''
-        return sorted(self._repo.dirstate.walk(match,
+        return sorted(self._repo.dirstate.walk(self._repo.narrowmatch(match),
                                                subrepos=sorted(self.substate),
                                                unknown=True, ignored=False))
 

tests/test-narrow-commit.t

@@ -91,8 +91,6 b' Can commit changes inside. Leaves outsid'
   created new head
   $ hg files -r .
   inside/f1
-  outside/f1 (flat !)
-  outside/ (tree !)
   $ hg manifest --debug
   3f4197b4a11b9016e77ebc47fe566944885fd11b 644   inside/f1
   7fb3bb6356d28d4dc352c5ba52d7350a81b6bd46 644   outside/f1 (flat !)