diff -r d5abe76da61e -r 2371f4aea665 mercurial/filemerge.py
--- a/mercurial/filemerge.py	Sat Nov 12 02:08:01 2011 +0100
+++ b/mercurial/filemerge.py	Wed Nov 16 18:04:19 2011 -0600
@@ -262,7 +262,11 @@
         _matcheol(repo.wjoin(fd), back)
 
     if r:
-        ui.warn(_("merging %s failed!\n") % fd)
+        if tool == "internal:merge":
+            ui.warn(_("merging %s incomplete! "
+                      "(edit conflicts, then use 'hg resolve --mark')\n") % fd)
+        else:
+            ui.warn(_("merging %s failed!\n") % fd)
     else:
         os.unlink(back)