title: Get list of changesets in a changegroup (mercurial python hook)
body: <p>I want a mercurial hook that will run JSLint/PyChecker/etc on all files that are modified. However, I do not have control over all hg clients, and want this to run on push to the master repository (which I have control), so a pretxnchangegroup hook on the master seems best.</p>
  
  <p>How can I get a list of all changesets that are in the changegroup that is going to be committed?</p>
  
  <p>I have seem other solutions that use a precommit hook, but these will not work for me because the clients may already have a commit that fails JSLint. In this case, they should be able to fix the errors in a new commit, and be able to push (both the bad and new commits) to the server successfully. The server just needs to check the most recent changeset on each branch, of every file that was modified in the changegroup.</p>