Re: [BUG?] fetch into shallow sends a large number of objects

On Tue, Mar 8, 2016 at 7:14 PM, Jeff King [off-list ref] wrote:

...

So I think the solution to both is that we need to do a _separate_
traversal with all of the positive tips we're going to send, and the
parents of any shallow commits the client has, to find their fork points
(i.e., merge bases). And then we add those fork points to the shallow
list (grafting out their parents), and communicate them to the client to
add to its shallow setup.

Good news. We have the mechanism in place, I think.
get_shallow_commits_by_rev_list() (from 'pu') will produce the right
shallow points for sending back to the client if you pass "--not
<current shallow points>" to it. It's meant to be used for
--shallow-exclude and --shallow-since, but if neither is given (nor
--depth) I guess we can run it with current shallow points. I wonder
if we can detect some common cases and avoid commit traversing this
way though.
-- 
Duy