diff -r 3a72c89a83ec -r b52404a914a9 hgext/schemes.py
--- a/hgext/schemes.py	Fri Feb 08 21:08:34 2013 +0000
+++ b/hgext/schemes.py	Thu Apr 11 14:41:22 2013 +0200
@@ -62,7 +62,10 @@
 
     def instance(self, ui, url, create):
         # Should this use the util.url class, or is manual parsing better?
-        url = url.split('://', 1)[1]
+        try:
+            url = url.split('://', 1)[1]
+        except IndexError:
+            raise util.Abort(_("no '://' in scheme url '%s'") % url)
         parts = url.split('/', self.parts)
         if len(parts) > self.parts:
             tail = parts[-1]