title: Git grep syntax with square brackets
body: <p>Why does <code>git log --grep=\[92\]</code> match the commit with the following message:</p>
  
  <pre><code>Author: Aston, Ben (Foo-UK) &lt;Ben.Aston@foo.co.uk&gt;
  Date:   Wed May 23 12:56:23 2012 +0000
  
  [83] Favourites icon addition for release. &lt;BA&gt;
  
  
  git-tfs-id: [http://fooppp012v:8080/tfs/TFS2010%20Collection]$/Foo/DnR;C210630
  </code></pre>
  
  <p>It seems that the correct regular expression format is not what I think?</p>