--- a/mercurial/commands.py	Sat Dec 05 23:16:09 2009 +0100
+++ b/mercurial/commands.py	Sat Dec 05 23:26:27 2009 -0500
@@ -1486,6 +1486,11 @@
             helplist(_('list of commands:\n\n'), select)
             return
 
+        # check if it's an invalid alias and display its error if it is
+        if getattr(entry[0], 'badalias', False):
+            entry[0](ui)
+            return
+
         # synopsis
         if len(entry) > 2:
             if entry[2].startswith('hg'):