manifest: fix _search() corner-case
It failed when searching the empty string in the null revision.
--- a/mercurial/manifest.py Mon Nov 24 17:16:39 2008 -0800
+++ b/mercurial/manifest.py Tue Nov 25 22:23:17 2008 +0100
@@ -63,6 +63,8 @@
while i < lenm and m[i] != c:
i += 1
return i
+ if not s:
+ return (lo, lo)
lenm = len(m)
if not hi:
hi = lenm