diff -r 30cb79d84352 -r 89e05c02a4af mercurial/merge.py
--- a/mercurial/merge.py	Mon Mar 16 16:58:41 2009 -0500
+++ b/mercurial/merge.py	Mon Mar 16 16:58:41 2009 -0500
@@ -14,9 +14,10 @@
     def __init__(self, repo):
         self._repo = repo
         self._read()
-    def reset(self, node):
+    def reset(self, node=None):
         self._state = {}
-        self._local = node
+        if node:
+            self._local = node
         shutil.rmtree(self._repo.join("merge"), True)
     def _read(self):
         self._state = {}