parse-options-cb: convert to struct object_id

This is a caller of lookup_commit_reference, which we will soon convert.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

parse-options-cb.c

@@ -80,14 +80,14 @@ int parse_opt_verbosity_cb(const struct option *opt, const char *arg,
 
 int parse_opt_commits(const struct option *opt, const char *arg, int unset)
 {
-	unsigned char sha1[20];
+	struct object_id oid;
 	struct commit *commit;
 
 	if (!arg)
 		return -1;
-	if (get_sha1(arg, sha1))
+	if (get_oid(arg, &oid))
 		return error("malformed object name %s", arg);
-	commit = lookup_commit_reference(sha1);
+	commit = lookup_commit_reference(oid.hash);
 	if (!commit)
 		return error("no such commit %s", arg);
 	commit_list_insert(commit, opt->value);