title: Hash collision in git
body: <p>What would actually happen if I had a hash collision while using git?</p>
  
  <p>E.g. I manage to commit two files with the same sha1 checksum,
  would git notice it or corrupt one of the files?</p>
  
  <p>Could git be improved to live with that, or would I have to change to a new hash algorithm?</p>
  
  <p>(Please do not deflect this question by discussing how unlikely that is - Thanks)</p>