Use release_revisions() on the the "struct rev_info" in
show_submodule_diff_summary() where we need to pre-initialize with "{
0 }" to make sure that we won't segfault when calling
release_revisions().

Most functions that use "struct rev_info" will call
repo_init_revisions() early, which will do an equivalent memset(). In
this case we might "goto out" before doing the equivalent of that
operation, see the "goto" on "(!left || !right || !sub)" added in
8e6df65015f (submodule: refactor show_submodule_summary with helper
function, 2016-08-31).

Signed-off-by: Ævar Arnfjörð Bjarmason <redacted>
---
 submodule.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/submodule.c b/submodule.c
index 0510cb193b6..285c1896c9e 100644
--- a/submodule.c
+++ b/submodule.c

@@ -638,7 +638,7 @@ void show_submodule_diff_summary(struct diff_options *o, const char *path,
 		struct object_id *one, struct object_id *two,
 		unsigned dirty_submodule)
 {
-	struct rev_info rev;
+	struct rev_info rev = { 0 };
 	struct commit *left = NULL, *right = NULL;
 	struct commit_list *merge_bases = NULL;
 	struct repository *sub;

@@ -664,6 +664,7 @@ void show_submodule_diff_summary(struct diff_options *o, const char *path,
 	print_submodule_diff_summary(sub, &rev, o);
 
 out:
+	release_revisions(&rev);
 	if (merge_bases)
 		free_commit_list(merge_bases);
 	clear_commit_marks(left, ~0);

-- 
2.35.1.1295.g6b025d3e231