title: git branch -r --merged not showing merged branches
body: <p>I am trying to tidy up our remote repository and I have some issue.</p>
  
  <p>I am trying to delete all remote branches which have been merged into anything (we had some strange workflow).</p>
  
  <p>The issue is that <code>git branch -r --merged</code> shows just couple of branches, when on our BitBucket I see dozens of branches marked as merged.</p>
  
  <p>The issue MAY BE related to the fact that I have run one script already:
  <code>git branch -r --merged | egrep "(^\*|feature|bugfix|hotfix)" | sed 's/origin\///' | xargs -n 1 git push --delete origin</code> which suppose to do that however it somehow worked - command progressed, pushed to origin but remote branches have not been deleted. </p>
  
  <p>Before that it was showing proper list of branches, but now something is not working as expected.</p>
  
  <p>Any idea how to fix it?</p>