title: Git commit on Windows (Cygwin) is broken.
body: <p>I've got a Cygwin install on Windows 7. Git was working great up until a few days ago, when commits just stopped working. Here's a log of a brand new repo:</p>
  
  <pre><code>wt@CO /cygdrive/u/Projects
  $ mkdir Temp
  
  wt@CO /cygdrive/u/Projects
  $ cd Temp/
  
  wt@CO /cygdrive/u/Projects/Temp
  $ touch Hello.txt
  
  wt@CO /cygdrive/u/Projects/Temp
  $ git init
  Initialized empty Git repository in /cygdrive/u/Projects/Temp/.git/
  
  wt@CO /cygdrive/u/Projects/Temp
  $ git add .
  
  wt@CO /cygdrive/u/Projects/Temp
  $ git commit -m "hi"
  error: invalid object 100644 e69de29bb2d1d6434b8b29ae775ad8c2e48c5391 for 'Hello
  .txt'
  error: Error building trees
  </code></pre>
  
  <p>I've Google-ed the hell out of it to no avail. What's going on here?</p>