--- a/mercurial/commands.py	Tue Nov 08 14:22:03 2005 -0800
+++ b/mercurial/commands.py	Wed Nov 09 12:52:05 2005 -0800
@@ -15,6 +15,8 @@
 
 class UnknownCommand(Exception):
     """Exception raised if command is not in the command table."""
+class AmbiguousCommand(Exception):
+    """Exception raised if command shortcut matches more than one command."""
 
 def filterfiles(filters, files):
     l = [x for x in files if x in filters]
@@ -387,7 +389,7 @@
         if with_version:
             show_version(ui)
             ui.write('\n')
-        key, i = find(cmd)
+        aliases, i = find(cmd)
         # synopsis
         ui.write("%s\n\n" % i[2])
 
@@ -399,9 +401,8 @@
 
         if not ui.quiet:
             # aliases
-            aliases = ', '.join(key.split('|')[1:])
-            if aliases:
-                ui.write(_("\naliases: %s\n") % aliases)
+            if len(aliases) > 1:
+                ui.write(_("\naliases: %s\n") % ', '.join(aliases[1:]))
 
             # options
             if i[1]:
@@ -2375,17 +2376,20 @@
           " debugindex debugindexdot paths")
 
 def find(cmd):
-    choice = []
+    """Return (aliases, command table entry) for command string."""
+    choice = None
     for e in table.keys():
         aliases = e.lstrip("^").split("|")
         if cmd in aliases:
-            return e, table[e]
+            return aliases, table[e]
         for a in aliases:
             if a.startswith(cmd):
-                choice.append(e)
-    if len(choice) == 1:
-        e = choice[0]
-        return e, table[e]
+                if choice:
+                    raise AmbiguousCommand(cmd)
+                else:
+                    choice = aliases, table[e]
+    if choice:
+        return choice
 
     raise UnknownCommand(cmd)
 
@@ -2423,7 +2427,8 @@
 
             cmd, args = args[0], args[1:]
 
-        i = find(cmd)[1]
+        aliases, i = find(cmd)
+        cmd = aliases[0]
         c = list(i[1])
     else:
         cmd = None
@@ -2503,6 +2508,9 @@
             u.warn(_("hg: %s\n") % inst.args[1])
             help_(u, 'shortlist')
         sys.exit(-1)
+    except AmbiguousCommand, inst:
+        u.warn(_("hg: command '%s' is ambiguous.\n") % inst.args[0])
+        sys.exit(1)
     except UnknownCommand, inst:
         u.warn(_("hg: unknown command '%s'\n") % inst.args[0])
         help_(u, 'shortlist')