Since 131b94a10a7 (test-lib.sh: Use GLIBC_TUNABLES instead of
MALLOC_CHECK_ on glibc >= 2.34, 2022-03-04) compiling with
SANITIZE=leak has missed reporting some leaks. The old MALLOC_CHECK
method used before glibc 2.34 seems to have been (mostly?) compatible
with it, but after 131b94a10a7 e.g. running:

	TEST_NO_MALLOC_CHECK=1 make SANITIZE=leak test T=t6437-submodule-merge.sh

Would report a leak in builtin/commit.c, but this would not:

	TEST_NO_MALLOC_CHECK= make SANITIZE=leak test T=t6437-submodule-merge.sh

Since the interaction is clearly breaking the SANITIZE=leak mode,
let's mark them as explicitly incompatible.

A related regression for SANITIZE=address was fixed in
067109a5e7d (tests: make SANITIZE=address imply TEST_NO_MALLOC_CHECK,
2022-04-09).

Signed-off-by: Ævar Arnfjörð Bjarmason <redacted>
---

Junio: I think this is worth considering for v2.38.0. We've had this
check since v2.36.0

But 2.34 just recently got migrated to Debian testing (just a few days
ago), I suspect other distros are either upgrading to it now, or will
soon: https://tracker.debian.org/pkg/glibc;

When I upgraded to it I discovered that all of our tests pass with
SANITIZE=leak, i.e. unless TEST_NO_MALLOC_CHECK=1 is provided we
completely disable the LeakSanitizer in favor of glibc.

 t/test-lib.sh | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/t/test-lib.sh b/t/test-lib.sh
index a65df2fd220..02f438d47ec 100644
--- a/t/test-lib.sh
+++ b/t/test-lib.sh

@@ -563,8 +563,10 @@ case $GIT_TEST_FSYNC in
 esac
 
 # Add libc MALLOC and MALLOC_PERTURB test only if we are not executing
-# the test with valgrind and have not compiled with SANITIZE=address.
+# the test with valgrind and have not compiled with conflict SANITIZE
+# options.
 if test -n "$valgrind" ||
+   test -n "$SANITIZE_LEAK" ||
    test -n "$SANITIZE_ADDRESS" ||
    test -n "$TEST_NO_MALLOC_CHECK"
 then