[PATCH] pull: gracefully recover from delta retrieval failure.

[PATCH] pull: gracefully recover from delta retrieval failure.

This addresses a concern raised by Jason McMullan in the mailing
list discussion.  After retrieving and storing a potentially
deltified object, pull logic tries to check and fulfil its delta
dependency.  When the pull procedure is killed at this point,
however, there was no easy way to recover by re-running pull,
since next run would have found that we already have that
deltified object and happily reported success, without really
checking its delta dependency is satisfied.

This patch introduces --recover option to git-*-pull family
which causes them to re-validate dependency of deltified objects
we are fetching.  A new test t5100-delta-pull.sh covers such a
failure mode.

Signed-off-by: Junio C Hamano <junkio@cox.net>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>