title: Is it possible to set a git commit to have a timestamp prior to 1970?
body: <p>Unix timestamps are signed 32 bit integers (64 bit on some systems today, or so I understand). On some software products this allows you to use dates going back as far as 1903 or so. </p>
  
  <p>However, when I try the following:</p>
  
  <pre><code>git commit -m "this is a test commit" --date="1960-04-07 18:00:00"
  </code></pre>
  
  <p>I receive an "fatal: invalid date format" error.</p>
  
  <p>This isn't very practical (I'm not a time-traveler), but I've been wondering about using git for historical purposes. Can this be forced with a git plumbing command? On a related note: does git always use a 32 bit timestamp, or does this depend on the environment it's built on?</p>