basefilectx: move _changeid from filectx

mercurial/context.py

@@ -423,6 +423,15 b' class basefilectx(object):'
     def _filelog(self):
         return self._repo.file(self._path)
 
+    @propertycache
+    def _changeid(self):
+        if '_changeid' in self.__dict__:
+            return self._changeid
+        elif '_changectx' in self.__dict__:
+            return self._changectx.rev()
+        else:
+            return self._filelog.linkrev(self._filerev)
+
 class filectx(basefilectx):
     """A filecontext object makes access to data related to a particular
        filerevision convenient."""
@@ -473,15 +482,6 b' class filectx(basefilectx):'
             return changectx(self._repo.unfiltered(), self._changeid)
 
     @propertycache
-    def _changeid(self):
-        if '_changeid' in self.__dict__:
-            return self._changeid
-        elif '_changectx' in self.__dict__:
-            return self._changectx.rev()
-        else:
-            return self._filelog.linkrev(self._filerev)
-
-    @propertycache
     def _filenode(self):
         if '_fileid' in self.__dict__:
             return self._filelog.lookup(self._fileid)