[push] Call the pre-push hook later in the push process

[push] Call the pre-push hook later in the push process

Call the pre-push hook only after having received the remote
advertisement and having determined rejections, like C git does.
Also similar to C git, don't pass rejected or up-to-date updates
to the pre-push hook.

Bug: 578852
Change-Id: I51d379ea7bd8234ec815f8f4a9fa325816f476cf
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>