title: How does a commit disappear from the log of one file?
body: <p>So I made a change to a file, pushed it to our main repo, saw it there.  David pulled from that repo and did -- well, something -- and couldn't see my change.  Since David is a typical Microsoft victim, I asked him to push what he had back to the repo and I'd look at it there.</p>
  
  <p><code>git log --name-only</code> produces</p>
  
  <pre><code>commit 194b7f5dbb59d29ace340a376f10906752978db5
  Merge: 484df79 afc2dec
  Author: David Good &lt;david@company.com&gt;
  Date:   Sat Sep 24 11:47:14 2011 -0700
  
  [ David's merge ]
  
  commit afc2dec4a828de05350c39526eeecf9d3a15e465
  Author: Michael &lt;info@company.com&gt;
  Date:   Sat Sep 24 10:58:54 2011 -0700
  
  [ my changes ]
  
  backend/theimportantfile.js
  
  commit e4e2f9ce9df3adf5ed0547ed16521eb742cc2ac1
  Author: Michael &lt;info@company.com&gt;
  Date:   Sat Sep 24 10:47:09 2011 -0700
  
  [ some other thing ]
  </code></pre>
  
  <p>but <code>git log backend/theimportantfile.js</code> produces</p>
  
  <pre><code>commit eb470fe1792220779b14e90337f74fb216fc9f7f
  Author: David Good &lt;david@company.com&gt;
  Date:   Mon Sep 12 17:20:25 2011 -0700
  
  [ comment ]
  
  commit 63ddd2be020092a4bf65d1eac106ece5fd7fbbd3
  Author: David Good &lt;david@company.com&gt;
  Date:   Fri Sep 9 16:23:53 2011 -0700
  
  [ comment ]
  </code></pre>
  
  <p>So according to git, <code>backend/theimportantfile.js</code> hasn't been touched in weeks but it was also changed two hours ago with the afc2dec commit.  How can I track down what happened?</p>