odb: return temporary ODB source when set

When invoked, `odb_set_temporary_primary_source()` installs a temporary
object directory as the new primary ODB source. A caller that wants to
operate on the ODB source of the open transaction must assume that it is
the first entry in the ODB source list which is a bit awkward and
fragile.

Instead, return the newly installed source directly and report the
previous primary source via a new `prev_source` out parameter. Propagate
the installed source through `tmp_objdir_replace_primary_odb()` and
start storing it in the "files" ODB transaction so a subsequent commit
can easily access it without relying on the ODB source list ordering.

Signed-off-by: Justin Tobler <jltobler@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

0 files changed, 0 insertions, 0 deletions