[xmonad] Upgrading repo formats

[Don Stewart]

spencerjanssen:
> I do support switching, but I do have one concern.  As I understand it,
> after switching we won't be able to apply any darcs 1 patches to the darcs 2
> repo.  We would need to resolve any outstanding forks and clean up all the
> pending patches on the mailing list.
> 
> Also, is there some documentation or a guide for converting?  I really don't
> want to screw up our repository.
> 

Can we test in parallel for a little while?