diff -r 85fd8402cbc4 -r d51630301241 mercurial/filemerge.py
--- a/mercurial/filemerge.py	Fri May 06 15:13:46 2011 +0200
+++ b/mercurial/filemerge.py	Fri May 06 15:16:22 2011 +0200
@@ -29,7 +29,7 @@
         k = _toolstr(ui, tool, kn)
         if not k:
             continue
-        p = util.lookup_reg(k, _toolstr(ui, tool, "regname"))
+        p = util.lookupreg(k, _toolstr(ui, tool, "regname"))
         if p:
             p = util.find_exe(p + _toolstr(ui, tool, "regappend"))
             if p: