diff -r aae338f9da70 -r ac41aa4a66ab mercurial/cmdutil.py
--- a/mercurial/cmdutil.py	Mon Mar 02 10:29:45 2015 -0600
+++ b/mercurial/cmdutil.py	Mon Mar 02 19:01:00 2015 +0000
@@ -2281,6 +2281,8 @@
                 date = ctx.date()
                 # Recompute copies (avoid recording a -> b -> a)
                 copied = copies.pathcopies(base, ctx)
+                if old.p2:
+                    copied.update(copies.pathcopies(old.p2(), ctx))
 
                 # Prune files which were reverted by the updates: if old
                 # introduced file X and our intermediate commit, node,