Fix a memory leak introduced in a310d43494 ([PATCH] Deltification
library work by Nicolas Pitre., 2005-05-19), as a result we can mark
another test as passing with SANITIZE=leak using
"TEST_PASSES_SANITIZE_LEAK=true".
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>