manifest: record the original revision when in -r mode.

Currently when doing a sync against a revision locked manifest,
sync has no option but to fall back to sync'ing the entire refs space;
it doesn't know which ref to ask for that contains the sha1 it wants.

This sucks if we're in -c mode; thus when we generate a revision
locked manifest, record the originating branch- and try syncing that
branch first.  If the sha1 is found within that branch, this saves
us having to pull down the rest of the repo- a potentially heavy
saving.

If that branch doesn't have the desired sha1, we fallback to sync'ing
everything.

Change-Id: I99a5e44fa1d792dfcada76956a2363187df94cf1

0 files changed, 0 insertions, 0 deletions