Parent Delta and Shallow Cloning

[Augie Fackler]

I think I'd like to roll the dice on the sahllow cloning project. I'm
torn on the parent deltas one, but Benoit pointed out in #hg-gsoc that
we haven't necessarily ironed out the wireproto bits.

What do other people feel? They're not duplicates, so we should be OK
to take both if we feel like it.

Also, I'd like to donate our slots we don't use to the Python Software
Foundation - anyone object?