--- a/mercurial/merge.py	Tue Sep 26 14:40:21 2006 -0500
+++ b/mercurial/merge.py	Wed Sep 27 09:35:53 2006 +0200
@@ -133,6 +133,10 @@
     Find moves and copies between m1 and m2 back to limit linkrev
     """
 
+    # avoid silly behavior for update from empty dir
+    if not m1:
+        return {}
+
     dcopies = repo.dirstate.copies()
     copy = {}
     match = {}
@@ -167,7 +171,12 @@
 
     return copy
 
-def manifestmerge(ui, m1, m2, ma, overwrite, backwards, partial):
+def filtermanifest(man, partial):
+    if partial:
+        for k in man.keys():
+            if not partial(k): del man[k]
+
+def manifestmerge(ui, m1, m2, ma, overwrite, backwards):
     """
     Merge manifest m1 with m2 using ancestor ma and generate merge action list
     """
@@ -183,13 +192,6 @@
         ui.debug(" %s: %s -> %s\n" % (f, msg, m))
         action.append((f, m) + args)
 
-    # Filter manifests
-    if partial:
-        for f in m1.keys():
-            if not partial(f): del m1[f]
-        for f in m2.keys():
-            if not partial(f): del m2[f]
-
     # Compare manifests
     for f, n in m1.iteritems():
         if f in m2:
@@ -356,19 +358,20 @@
                   (short(p1), short(p2), short(pa)))
 
     action = []
-
     copy = {}
-    if not (backwards or overwrite):
-        copy = findcopies(repo, m1, m2, repo.changelog.rev(pa))
 
     m1 = workingmanifest(repo, m1, status)
+    filtermanifest(m1, partial)
+    filtermanifest(m2, partial)
 
     if not force:
         checkunknown(repo, m2, status)
     if not branchmerge:
         action += forgetremoved(m2, status)
+    if not (backwards or overwrite):
+        copy = findcopies(repo, m1, m2, repo.changelog.rev(pa))
 
-    action += manifestmerge(repo.ui, m1, m2, ma, overwrite, backwards, partial)
+    action += manifestmerge(repo.ui, m1, m2, ma, overwrite, backwards)
     del m1, m2, ma
 
     ### apply phase