title: git commit stopped working - Error building trees
body: <p>I can not commit a change:</p>
  
  <pre><code>$ git commit
  error: invalid object 100644 13da9eeff5a9150cf2135aaed4d2e337f97b8114 for 'spec/routing/splits_routing_spec.rb'
  error: Error building trees
  </code></pre>
  
  <p>I tried so far:</p>
  
  <pre><code>$ git fsck | grep 13da
  missing blob 13da9eeff5a9150cf2135aaed4d2e337f97b8114
  </code></pre>
  
  <p>and also:</p>
  
  <pre><code>$ git prune
  error: Could not read 1394dce6fd1ad15a70b2f2623509082007dc5b6c
  fatal: bad tree object 1394dce6fd1ad15a70b2f2623509082007dc5b6c
  </code></pre>
  
  <p>and also:</p>
  
  <pre><code>$ git fsck | grep 13da
  missing blob 13da9eeff5a9150cf2135aaed4d2e337f97b8114
  </code></pre>
  
  <p>but nothing helped. Should I delete the file, commit and reintroduce back? I am willing to lose little bit of history if it brings git commit back.</p>