title: Tried to remove files from git, now branches are diverged and I can't push the changes
body: <p>This is the first time for me using git (on bitbucket.org - if that makes any difference) and I committed a few audio files to the repo which I obviously don't want there. I added then added the paths to the .gitignore to find out that this will only ignore further changes.
  So I stumbled upon <a href="https://stackoverflow.com/questions/872565/remove-sensitive-files-and-their-commits-from-git-history">this SO question</a> and tried to use <a href="http://dound.com/2009/04/git-forever-remove-files-or-folders-from-history/" rel="nofollow noreferrer">David Underhill's script</a> that's mentioned there.</p>
  
  <p>However, now I'm getting the following message for <code>git commit</code>:</p>
  
  <pre><code># On branch master
  # Your branch and 'origin/master' have diverged,
  # and have 10 and 10 different commits each, respectively.
  #
  nothing to commit (working directory clean)
  </code></pre>
  
  <p>and for <code>git push</code></p>
  
  <pre><code> ! [rejected]        master -&gt; master (non-fast-forward)
  error: failed to push some refs to 'https://bitbucket.org/abc/def'
  To prevent you from losing history, non-fast-forward updates were rejected
  Merge the remote changes (e.g. 'git pull') before pushing again.  See the
  'Note about fast-forwards' section of 'git push --help' for details.
  </code></pre>
  
  <p>So I tried a <code>git push --force</code> which succeeded but didn't actually change anything in the repo and doesn't even show up there.</p>
  
  <p>Do you know how I could fix this?</p>