[PATCH 0/4] Spend more effort in git-fetch-pack finding common revisions

This series of 4 patches extends the fetch-pack/upload-pack protocol such
that more than just one common revision is used to find out which objects
are needed by the client.

This means that the client spends more time on enumerating candidates, and
the server just acknowledges those it knows about. That is done until the
client runs out of candidates, or the server got HAS_MAX common revisions.

While it does not make much of a difference when you are tracking one linear
branch on one repository, this change should make it more efficient (and
also ease the burden on the server) to work with several repositories having
several branches, and intertwined development.

Next thing I'll do is write some nasty test cases.

Flame on,
Dscho