title: Git pull using GitPython + SSH keys doesn't work
body: <p>I am trying to pull a repo from my Github account using GitPython. This is after </p>
  
  <p>(1) I performed a git clone already from the command line.</p>
  
  <p>(2) Generated new SSH keys using </p>
  
  <pre><code>ssh-keygen -t rsa -b 4096
  </code></pre>
  
  <p>(3) Setup the contents of the .pub file from #2 above in Github as a new SSH key.</p>
  
  <p>I still get prompted to enter my Github username and password. Why is that ?</p>
  
  <p>Here is the config in my .git folder. Note the http:// in the url instead of https://</p>
  
  <pre><code>[core]
      repositoryformatversion = 0
      filemode = true
      bare = false
      logallrefupdates = true
  [remote "origin"]
      url = http://github.com/githubuser/myrepo.git
      fetch = +refs/heads/*:refs/remotes/origin/*
  [branch "master"]
      remote = origin
      merge = refs/heads/master
  </code></pre>
  
  <p>Here is my code snippet</p>
  
  <pre><code>import git, os
  
  DIR_NAME = 'path/to/dir/with/gitfolder'
  git_ssh_identity_file = os.path.expanduser('/path/to/rsa/key')
  git_ssh_cmd = 'ssh -i %s' % git_ssh_identity_file
  
  with git.Git().custom_environment(GIT_SSH_COMMAND=git_ssh_cmd):
  
      repo = git.Repo.init(DIR_NAME)
      origin = repo.remote()
      refs = origin.refs
  
      for ref in refs:
          if ref.remote_head == "master":
              origin.pull(ref.remote_head)
  </code></pre>