--- a/hgext/drophack.py	Mon Feb 24 19:01:12 2014 -0800
+++ b/hgext/drophack.py	Tue Feb 25 11:14:37 2014 -0800
@@ -71,11 +71,10 @@
     del repo.obsstore # drop the cache
     newstore = repo.obsstore
     assert not newstore # should be empty after rename
+    newmarkers = [m for m in oldmarkers if m not in markers]
     tr = repo.transaction('drophack')
     try:
-        for m in oldmarkers:
-            if m not in markers:
-                newstore.add(tr, [m])
+        newstore.add(tr, newmarkers)
         tr.close()
     finally:
         tr.release()