title: Git Merge Branch-Specific changes to other branch, ignoring merges
body: <p>I'm wondering if there's a good way to merge changes specific to a branch to another branch.</p>
  <p>Lets say I have a master branch, with changes A,B,C,D and E.   I create a feature branch for feature 1 which splits off the master from B.  The feature branch has changes M, and N, and then is merged back with the master, such that it contains C' and D', and a then a new feature2 specific change O is added.
  At the same time, another team creates another feature branch (feature2) split off of A, and makes changes X and Y.   What I'd like to do is merge the feature1 specific changes into the feature2 branch without grabbing any of the Branch1 specific changes (so, in the diagram below, I would want to merge changes M, N, and O to feature2, but I don't want B, C, D or E...</p>
  <pre><code>   A -- B -- C -- D -- E               (master)
      \    \         \ 
       \    M -- N -- (C'/D') -- O       (feature1)
        \                         \
         \                         \
          \-- X -- Y ------------  (M'/N'/O')     (feature2)
  </code></pre>
  <p>Now, in real life, the diagram is much more complex (there are several merges from master, and other branches into feature1).   Is there any way to grab only the commits that are specific to the feature1 branch and merge them onto feature2? (which will avoid conflicts when merging feature1 and feature2 back into master?)</p>