diff -r 972d4e0c3d44 -r 565f057bdc08 src/topic/__init__.py
--- a/src/topic/__init__.py	Fri Jun 19 16:16:42 2015 -0500
+++ b/src/topic/__init__.py	Fri Jun 19 16:23:29 2015 -0500
@@ -63,6 +63,12 @@
                 current = self.currenttopic
                 if current:
                     ctx.extra()[constants.extrakey] = current
+            if (isinstance(ctx, context.memctx) and
+                ctx.extra().get('amend_source') and
+                ctx.topic() and
+                not self.currenttopic):
+                # we are amending and need to remove a topic
+                del ctx.extra()[constants.extrakey]
             return orig.commitctx(self, ctx, error=error)
 
         @property