show-branch: simplify rev_is_head()

Only one of the callers of rev_is_head() provides two hashes to compare.
Move that check there and convert it to struct object_id.

Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/show-branch.c

@@ -482,10 +482,9 @@ static void snarf_refs(int head, int remotes)
 	}
 }
 
-static int rev_is_head(const char *head, const char *name,
-		       unsigned char *head_sha1, unsigned char *sha1)
+static int rev_is_head(const char *head, const char *name)
 {
-	if (!head || (head_sha1 && sha1 && !hasheq(head_sha1, sha1)))
+	if (!head)
 		return 0;
 	skip_prefix(head, "refs/heads/", &head);
 	if (!skip_prefix(name, "refs/heads/", &name))
@@ -806,9 +805,7 @@ int cmd_show_branch(int ac, const char **av, const char *prefix)
 			/* We are only interested in adding the branch
 			 * HEAD points at.
 			 */
-			if (rev_is_head(head,
-					ref_name[i],
-					head_oid.hash, NULL))
+			if (rev_is_head(head, ref_name[i]))
 				has_head++;
 		}
 		if (!has_head) {
@@ -867,10 +864,8 @@ int cmd_show_branch(int ac, const char **av, const char *prefix)
 	if (1 < num_rev || extra < 0) {
 		for (i = 0; i < num_rev; i++) {
 			int j;
-			int is_head = rev_is_head(head,
-						  ref_name[i],
-						  head_oid.hash,
-						  rev[i]->object.oid.hash);
+			int is_head = rev_is_head(head, ref_name[i]) &&
+				      oideq(&head_oid, &rev[i]->object.oid);
 			if (extra < 0)
 				printf("%c [%s] ",
 				       is_head ? '*' : ' ', ref_name[i]);