remotefilelog: use raw strings when looking for variable names

Keys in self.__dict__ and vars() are always str. So we need to use
raw strings to ensure lookups work on Python 3.

# skip-blame just r'' prefixes

Differential Revision: https://phab.mercurial-scm.org/D5957

hgext/remotefilelog/remotefilectx.py

@@ -39,11 +39,11 b' class remotefilectx(context.filectx):'
 
     @propertycache
     def _changeid(self):
-        if '_changeid' in self.__dict__:
+        if r'_changeid' in self.__dict__:
             return self._changeid
-        elif '_changectx' in self.__dict__:
+        elif r'_changectx' in self.__dict__:
             return self._changectx.rev()
-        elif '_descendantrev' in self.__dict__:
+        elif r'_descendantrev' in self.__dict__:
             # this file context was created from a revision with a known
             # descendant, we can (lazily) correct for linkrev aliases
             linknode = self._adjustlinknode(self._path, self._filelog,
@@ -102,7 +102,7 b' class remotefilectx(context.filectx):'
         """
         lkr = self.linkrev()
         attrs = vars(self)
-        noctx = not ('_changeid' in attrs or '_changectx' in attrs)
+        noctx = not (r'_changeid' in attrs or r'_changectx' in attrs)
         if noctx or self.rev() == lkr:
             return lkr
         linknode = self._adjustlinknode(self._path, self._filelog,