--- a/mercurial/merge.py
+++ b/mercurial/merge.py
@@ -203,8 +203,6 @@ def update(repo, node, branchmerge=False
action = []
# update m1 from working dir
- umap = dict.fromkeys(unknown)
-
for i,l in (("a", added), ("m", modified), ("u", unknown)):
for f in l:
m1[f] = m1.get(f, nullid) + i