Attached a set up script to reproduce a test environment for the hook.

Create an empty dir and run ``sh setup.sh`` in it.  This will:
  1) create a 'c1' subdir which is a cpython-like repo with the branches 2.7, 3.1, 3.2, default;
  2) download and set up the hook for this repo; 
  3) create a 'c2' clone of 'c1';

Once the clones are created, cd in 'c2', try to commit something, and push it.

Use `hg up <branchname>` to switch between branches.

If you `hg up 3.1`, change something, commit, and push, the hook will tell you that you have to merge with 3.2, if you do the same on 3.2 it will say you have to merge with default.

You can try unusual combinations (e.g. null merges, rollbacks, multiple commits per branch, etc.) to see how well the hook works.