title: How to abort an interactive rebase if --abort doesn't work?
body: <p>I've got myself into a muddle via an interactive rebase, and I now wish to abort it.  (i.e. go back to the point before I was dropped into interactive rebase mode, in my case via <code>git pull --rebase</code>.)  The way to do this seems to be via <code>git rebase --abort</code>, but this doesn't work:</p>
  
  <pre><code>$ git rebase --abort
  error: Ref refs/heads/master is at 55b388c141b1485b1acd9e050dbeb0eb90ef2ee7 but
  expected b918ac16a33881ce00799bea63d9c23bf7022d67
  fatal: Cannot lock the ref 'refs/heads/master'.
  Could not move back to refs/heads/master
  </code></pre>
  
  <p>How can I get out of interactive rebase mode, and clean up all references to it?  (<code>git reset --hard</code> succeeds, but doesn't drop me out of rebase mode.)</p>