title: Cocoapods and forked repo issue
body: <p>So here's my podfile:</p>
  
  <pre><code>workspace 'WSPhoto.xcworkspace'
  platform :ios, :deployment_target =&gt; "6.1"
  
  xcodeproj 'WSPhoto'
  
  pod 'Parse-iOS-SDK', '~&gt; 1.2.17'
  pod 'REActivityViewController',  :git =&gt; 'https://github.com/ramsel/REActivityViewController.git', :commit =&gt; 'f027011e8159393cf678d7c67c408891b609a6ef'
  pod 'SWTableViewCell', :git =&gt; 'https://github.com/ramsel/SWTableViewCell.git', :commit =&gt; '6f4e55e554c1b26ff3c850eb331273b536e4f900'
  pod 'ELCImagePickerController', '~&gt; 0.2.0'
  pod 'ChimpKit'
  </code></pre>
  
  <p>I'm forking a couple repos and pointing Cocoapods to specific commits of my forks based on the advice in my previous question: </p>
  
  <p><a href="https://stackoverflow.com/questions/20936885/cocoapods-and-github-fork">CocoaPods and GitHub forks</a></p>
  
  <p>However, I get the following error on <code>pod install --verbose</code>:</p>
  
  <pre><code>Fetching external sources
  -&gt; Pre-downloading: `REActivityViewController` from `https://github.com/ramsel/REActivityViewController.git`, commit `f027011e8159393cf678d7c67c408891b609a6ef`
   &gt; GitHub download
     $ /usr/bin/git config core.bare
     true
     $ /usr/bin/git config core.bare
     true
     $ /usr/bin/git rev-list --max-count=1
     f027011e8159393cf678d7c67c408891b609a6ef
     fatal: bad object f027011e8159393cf678d7c67c408891b609a6ef
     [!] Failed: /usr/bin/git rev-list --max-count=1
     f027011e8159393cf678d7c67c408891b609a6ef
   &gt; Cloning to Pods folder
       $ /usr/bin/git clone
       "/Users/admin/Library/Caches/CocoaPods/GitHub/4a2fb7e9e50f5b0922a251d6b2763
       d6d37629fda"
       "/Users/admin/Dropbox/Apps/things/Pods/REActivityViewController"
       Cloning into '/Users/admin/Dropbox/Apps/things/Pods/REActivityViewController'...
       done.
       Checking connectivity... done
     $ /usr/bin/git checkout -b activated-pod-commit
     f027011e8159393cf678d7c67c408891b609a6ef 2&gt;&amp;1
     fatal: reference is not a tree: f027011e8159393cf678d7c67c408891b609a6ef
  [!] Pod::Executable checkout -b activated-pod-commit f027011e8159393cf678d7c67c408891b609a6ef 2&gt;&amp;1
  
  fatal: reference is not a tree: f027011e8159393cf678d7c67c408891b609a6ef
  </code></pre>
  
  <p>I tried referencing a different my fork of <code>REActivityViewController</code> but same error. I commented out the <code>REActivityViewController</code> line in my podfile and the fork of SWTableViewCell install fine. </p>
  
  <p>So I'm thinking it's something particular to my <code>REActivityViewController</code> fork but it's not particular to a specific commit in that fork.</p>