basefilectx: move _filerev from filectx

mercurial/context.py

@@ -439,6 +439,10 b' class basefilectx(object):'
         else:
             return self._changectx.filenode(self._path)
 
+    @propertycache
+    def _filerev(self):
+        return self._filelog.rev(self._filenode)
+
 class filectx(basefilectx):
     """A filecontext object makes access to data related to a particular
        filerevision convenient."""
@@ -489,10 +493,6 b' class filectx(basefilectx):'
             return changectx(self._repo.unfiltered(), self._changeid)
 
     @propertycache
-    def _filerev(self):
-        return self._filelog.rev(self._filenode)
-
-    @propertycache
     def _repopath(self):
         return self._path