title: Merging changes to a folder from another repository
body: <p>We have a git repository <code>ProjA</code> with a plugin stored in <code>/plugins/foo</code>.
  After this project was completed, a second repository <code>ProjB</code> was started. Somewhere along the line foo was added to the repo like so</p>
  
  <pre><code>cp ../ProjA/plugins/foo plugins/foo
  git add .
  git commit -m "Added Foo Plugin"
  </code></pre>
  
  <p>followed immediately by</p>
  
  <pre><code>git mv plugins/foo plugins/foobar
  git commit -m "Fixed naming conflict with Foo"
  </code></pre>
  
  <p>Then a bunch of work was done.</p>
  
  <p>How do I merge all the changes (and more importantly history) to <code>ProjB/plugins/foobar</code> into <code>ProjA/plugins/foo</code> without any of the other changes in <code>ProjB/</code>?<br>
  I've tried creating a subtree and merge it in but all the changes were in <code>/</code> and there were no common ancestors to merge with.<br>
  Then I tried using <code>git format-patch</code> but I couldn't work out how to make it only apply to a subdirectory.<br>
  My best guess is to somehow combine the two actions but I don't know how to deal with the paths.</p>