narrowrevlog: add a TODO around remotefilelog moving to core

We should clean this up considerably when remotefilelog lands, which
we expect to try and accomplish in the near-ish future.

Differential Revision: https://phab.mercurial-scm.org/D2189

hgext/narrow/narrowrevlog.py

@@ -156,6 +156,10 b' def makenarrowfilelog(fl, narrowmatch):'
             # rename-checking logic when on remotefilelog. This
             # might be incorrect on other non-revlog-based storage
             # engines, but for now this seems to be fine.
+            #
+            # TODO: when remotefilelog is in core, improve this to
+            # explicitly look for remotefilelog instead of cheating
+            # with a hasattr check.
             if util.safehasattr(self, 'node'):
                 node = self.node(rev)
                 # Because renamed() is overridden above to