committablectx: cache _status in _poststatus

A future patch will remove the old workingctx.status which caches the status of
the working directory, therefore we now cache this status in the poststatus
hook of committablectx.

mercurial/context.py

@@ -1313,6 +1313,7 b' class workingctx(committablectx):'
         susposed to be linking to.
         """
         s[0] = self._filtersuspectsymlink(s[0])
+        self._status = s
         return s
 
     def _dirstatestatus(self, match=None, ignored=False, clean=False,