Change the way aliases to subcommands are handled.

cmd/juju/destroymachine.go

 package main
 
 import (
         "fmt"
         "launchpad.net/gnuflag"
         "launchpad.net/juju-core/cmd"
         "launchpad.net/juju-core/juju"
         "launchpad.net/juju-core/state"
 )
 
 // DestroyMachineCommand causes an existing machine to be destroyed.
 type DestroyMachineCommand struct {
         EnvName    string
         MachineIds []string
 }
 
 func (c *DestroyMachineCommand) Info() *cmd.Info {
-        return cmd.NewInfo(
-                "destroy-machine", "<machine> [, ...]", "destroy machines",
-                "Machines that have assigned units, or are responsible for the environment, cannot be destroyed.",
-                "terminate-machine")
+        return &cmd.Info{
+                Name:    "destroy-machine",
+                Args:    "<machine> ...",
+                Purpose: "destroy machines",
+                Doc:     "Machines that have assigned units, or are responsible for the environment, cannot be destroyed.",
+                Aliases: []string{"terminate-machine"},
+        }
 }
 
 func (c *DestroyMachineCommand) SetFlags(f *gnuflag.FlagSet) {
         addEnvironFlags(&c.EnvName, f)
 }
 
 func (c *DestroyMachineCommand) Init(args []string) error {
         if len(args) == 0 {
                 return fmt.Errorf("no machines specified")
         }
         for _, id := range args {
                 if !state.IsMachineId(id) {
                         return fmt.Errorf("invalid machine id %q", id)
                 }
         }
         c.MachineIds = args
         return nil
 }
 
 func (c *DestroyMachineCommand) Run(_ *cmd.Context) error {
         conn, err := juju.NewConnFromName(c.EnvName)
         if err != nil {
                 return err
         }
         defer conn.Close()
         return conn.DestroyMachines(c.MachineIds...)
 }