add prechangegroup and pretxnchangegroup hooks.
prechangegroup lets you stop push, pull or unbundle before it begins.
pretxnchangegroup lets you inspect changegroup before transaction is
committed, and roll back if you not like it.
removing b
this update spans a branch affecting the following files:
b
aborting update spanning branches!
(use update -m to merge across branches or -C to lose changes)