git-stash.sh: don't default to refs/stash if invalid ref supplied

   commit da65e7c133cd316c9076fbb6b0aeee7bc42a6db8
   Author: Brandon Casey <casey@nrlssc.navy.mil>
   Date:   Tue Sep 23 18:57:09 2008 -0500

       git-stash.sh: don't default to refs/stash if invalid ref supplied
    
       <snip>
    
       e.g. 'git stash apply stash@{1}' would fall back to
            'git stash apply stash@{0}'

heh, you fixed my spelling "mistake" :), but it wasn't a mistake. Originally I had:

    e.g. 'git stash apply stahs@{1}' would fall back to
         'git stash apply stash@{0}'

intending to show that a simple spelling mistake could cause the wrong thing to be done. The example in the commit message could actually still happen if there was only a single stash entry. I guess I should have used 'foobar@{1}'. :)

-brandon