commit.c: free() revs.commit in get_fork_point()

Fix a memory leak that's been with us since d96855ff51 (merge-base:
teach "--fork-point" mode, 2013-10-23).

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

commit.c

@@ -1033,6 +1033,7 @@ struct commit *get_fork_point(const char *refname, struct commit *commit)
 	ret = bases->item;
 
 cleanup_return:
+	free(revs.commit);
 	free_commit_list(bases);
 	free(full_refname);
 	return ret;

t/t3431-rebase-fork-point.sh

@@ -8,6 +8,7 @@ test_description='git rebase --fork-point test'
 GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
 export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 # A---B---D---E    (main)

t/t3432-rebase-fast-forward.sh

@@ -8,6 +8,7 @@ test_description='ensure rebase fast-forwards commits when possible'
 GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
 export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success setup '