The code that splits the object list amongst work threads tries to do so
on "path" boundaries not to prevent good delta matches. However, in
some cases, a few paths may largely dominate the hash distribution and
it is not possible to have good load balancing without ignoring those
boundaries.
Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>