title: No submodule mapping found in .gitmodule for a path that's not a submodule
body: <p>I have a project that has a submodule at <code>lib/three20</code></p>
  
  <p>My <code>.gitmodule</code> file looks like this:</p>
  
  <pre><code>[submodule "lib/three20"]
      path = lib/three20
      url = git://github.com/facebook/three20.git
  </code></pre>
  
  <p>I have cloned this in the past without errors, (<code>git submodule init</code> followed by a <code>git submodule update</code>) and it's been working for a while.</p>
  
  <p>I tried to clone this to a new machine, and now I'm getting this error on <code>git submodule init</code>:</p>
  
  <pre><code>No submodule mapping found in .gitmodules for path 'Classes/Support/Three20'
  </code></pre>
  
  <p>That path is just an empty folder in Xcode that I use to house the projects from the other directory.  It's not part of the <code>.gitmodules</code> file, so I don't see where it's getting this path from.</p>
  
  <p>Any ideas?</p>