hgext/remotefilelog/remotefilectx.py

--- a/hgext/remotefilelog/remotefilectx.py	Thu Feb 21 21:27:42 2019 -0800
+++ b/hgext/remotefilelog/remotefilectx.py	Sun Mar 25 21:32:16 2018 -0700
@@ -136,6 +136,10 @@
                 pass
         return renamed
 
+    def copysource(self):
+        copy = self.renamed()
+        return copy and copy[0]
+
     def ancestormap(self):
         if not self._ancestormap:
             self._ancestormap = self.filelog().ancestormap(self._filenode)