sha1-name.c: remove implicit dependency on the_index

This kills the_index dependency in get_oid_with_context() but for
get_oid() and friends, they still assume the_repository (which also
means the_index).

Unfortunately the widespread use of get_oid() will make it hard to
make the conversion now. We probably will add repo_get_oid() at some
point and limit the use of get_oid() in builtin/ instead of forcing
all get_oid() call sites to carry struct repository.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/builtin/rev-parse.c b/builtin/rev-parse.c
index 10d4dab..910a71e 100644
--- a/builtin/rev-parse.c
+++ b/builtin/rev-parse.c
@@ -933,7 +933,8 @@ int cmd_rev_parse(int argc, const char **argv, const char *prefix)
 			name++;
 			type = REVERSED;
 		}
-		if (!get_oid_with_context(name, flags, &oid, &unused)) {
+		if (!get_oid_with_context(the_repository, name,
+					  flags, &oid, &unused)) {
 			if (verify)
 				revs_count++;
 			else