title: How do you continue merging (or rebasing) after filter-branch?
body: <p>We have run filter-branch on a branch m (master) from some other repo to remove a large file, and pushed the resulting m' branch into github. We commit some patches to other branches based off m' (t, or topic). </p>
  
  <p>Is there some good way continue to merge (or rebase) new changes from m into m' so that we could propagate them to t' branches?
  The attached image shows what I'm trying to achieve (note that there would be more commits on every part of the tree, i.e. m3 is not just one commit).</p>
  
  <p>The closest I've come up with is</p>
  
  <pre><code>git rebase -f --onto m' [the m equivalent of m' head that you have to look up] m
  </code></pre>
  
  <p>i.e. for the picture</p>
  
  <pre><code>git rebase -f --onto m' m2 m
  </code></pre>
  
  <p>But that's a big pain (it's a rebase AND you have to look up m2 commit hash manually). 
  Is there a better way?</p>
  
  <p><a href="http://i.imgur.com/gBuQAtx.png" rel="nofollow">The approximate process</a></p>