mercurial/dispatch.py

--- a/mercurial/dispatch.py	Tue Mar 27 14:37:17 2012 -0500
+++ b/mercurial/dispatch.py	Tue Mar 27 16:17:46 2012 -0500
@@ -218,7 +218,7 @@
 
 def aliasargs(fn, givenargs):
     args = getattr(fn, 'args', [])
-    if args and givenargs:
+    if args:
         cmd = ' '.join(map(util.shellquote, args))
 
         nums = []
@@ -227,7 +227,7 @@
             nums.append(num)
             if num < len(givenargs):
                 return givenargs[num]
-            return ''
+            raise util.Abort(_('too few arguments for command alias'))
         cmd = re.sub(r'\$(\d+|\$)', replacer, cmd)
         givenargs = [x for i, x in enumerate(givenargs)
                      if i not in nums]