diff -r c624fb2c4239 -r 28a302e9225d mercurial/context.py
--- a/mercurial/context.py	Mon Dec 29 23:40:24 2014 -0800
+++ b/mercurial/context.py	Wed Dec 24 03:26:48 2014 -0800
@@ -877,10 +877,11 @@
             return pl
 
         # use linkrev to find the first changeset where self appeared
-        if self.rev() != self.linkrev():
-            base = self.filectx(self.filenode())
-        else:
-            base = self
+        base = self
+        introrev = self.introrev()
+        if self.rev() != introrev:
+            base = filectx(self._repo, self._path, filelog=self.filelog(),
+                           fileid=self.filenode(), changeid=introrev)
 
         # This algorithm would prefer to be recursive, but Python is a
         # bit recursion-hostile. Instead we do an iterative