--- a/mercurial/hg.py	Wed Mar 30 20:01:47 2011 -0700
+++ b/mercurial/hg.py	Wed Mar 30 20:02:07 2011 -0700
@@ -69,11 +69,8 @@
 }
 
 def _lookup(path):
-    scheme = 'file'
-    if path:
-        c = path.find(':')
-        if c > 0:
-            scheme = path[:c]
+    u = url.url(path)
+    scheme = u.scheme or 'file'
     thing = schemes.get(scheme) or schemes['file']
     try:
         return thing(path)