Fix a logic error in the initial introduction of DC_SHA1_EXTERNAL. If
git.git has a sha1collisiondetection submodule checked out the logic
to set DC_SHA1_SUBMODULE=auto would interact badly with the check for
whether DC_SHA1_SUBMODULE was set.
It would error out, meaning that there's no way to build git with
DC_SHA1_EXTERNAL=YesPlease without deinit-ing the submodule.
Instead, adjust the logic to only fire if the variable is to something
else than "auto" which would mean it's a mistake on the part of
whoever's building git, not just the Makefile tripping over its own
logic.
1.
3964cbbb5c ("sha1dc: allow building with the external sha1dc
library", 2017-08-15)
2.
cac87dc01d ("sha1collisiondetection: automatically enable when
submodule is populated", 2017-07-01)
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>