title: How can I override the settings Rails inherits from my environment?
body: <p>I changed the program in my <code>.profile</code> used by <code>git diff</code> to one of my own, which breaks the diffs in a Redmine application.</p>
  
  <p><code>ssdiff.sh</code> is a call to <code>vimdiff -R</code> which displays the side by side diffs I prefer.</p>
  
  <pre><code># environment variables
  GIT_EXTERNAL_DIFF=$HOME/bin/ssdiff.sh
  export GIT_EXTERNAL_DIFF
  </code></pre>
  
  <p>This resulted in diffs in the Redmine app not working.</p>
  
  <p>How can I override the environment settings in the Rails application back to the defaults expected by Redmine?</p>