title: Push to github gist failing
body: <p>Trying to push a PNG to my github gist without success.</p>
  
  <pre><code>$ git clone https://gist.github.com/6124716.git
  $ cd 6124716
  $ ls
  fed.json     index.html     vermont.json
  </code></pre>
  
  <p>I can then modify index.html and push the change to my github repository. However once I save a png file to the repo I lose the ability to push:</p>
  
  <pre><code>$ git push
  Counting objects: 4, done.
  Delta compression using up to 4 threads.
  Compressing objects: 100% (3/3), done.
  Writing objects: 100% (3/3), 25.48 KiB, done.
  Total 3 (delta 0), reused 0 (delta 0)
  error: RPC failed; result=52, HTTP code = 0
  fatal: The remote end hung up unexpectedly
  fatal: The remote end hung up unexpectedly
  </code></pre>
  
  <p>Reading about the problem, I've seen suggestions to increase the buffer size:</p>
  
  <pre><code>$ git config http.postBuffer 524288000
  </code></pre>
  
  <p>But I still get the same error message. Furthermore, vermont.json is much larger than the PNG I am trying to upload.</p>
  
  <pre><code>$ ls -la
  drwxr-xr-x   7 mparrilla  staff     238 Aug  2 09:53 .
  drwxr-xr-x   7 mparrilla  staff     238 Aug  2 09:53 ..
  drwxr-xr-x  14 mparrilla  staff     476 Aug  2 09:56 .git
  -rw-r--r--   1 mparrilla  staff    5635 Aug  2 09:52 fed.json
  -rw-r--r--   1 mparrilla  staff    3381 Aug  2 09:52 index.html
  -rw-r--r--   1 mparrilla  staff   25776 Aug  2 09:28 thumbnail.png
  -rw-r--r--   1 mparrilla  staff  187388 Aug  2 09:52 vermont.json
  </code></pre>