blame: extract find_single_final

Signed-off-by: Max Kirillov <max@max630.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/blame.c

@@ -2396,16 +2396,11 @@ static struct commit *fake_working_tree_commit(struct diff_options *opt,
 	return commit;
 }
 
-static char *prepare_final(struct scoreboard *sb)
+static struct object_array_entry *find_single_final(struct rev_info *revs)
 {
 	int i;
-	const char *final_commit_name = NULL;
-	struct rev_info *revs = sb->revs;
+	struct object_array_entry *found = NULL;
 
-	/*
-	 * There must be one and only one positive commit in the
-	 * revs->pending array.
-	 */
 	for (i = 0; i < revs->pending.nr; i++) {
 		struct object *obj = revs->pending.objects[i].item;
 		if (obj->flags & UNINTERESTING)
@@ -2414,14 +2409,24 @@ static char *prepare_final(struct scoreboard *sb)
 			obj = deref_tag(obj, NULL, 0);
 		if (obj->type != OBJ_COMMIT)
 			die("Non commit %s?", revs->pending.objects[i].name);
-		if (sb->final)
+		if (found)
 			die("More than one commit to dig from %s and %s?",
 			    revs->pending.objects[i].name,
-			    final_commit_name);
-		sb->final = (struct commit *) obj;
-		final_commit_name = revs->pending.objects[i].name;
+			    found->name);
+		found = &(revs->pending.objects[i]);
+	}
+	return found;
+}
+
+static char *prepare_final(struct scoreboard *sb)
+{
+	struct object_array_entry *found = find_single_final(sb->revs);
+	if (found) {
+		sb->final = (struct commit *) found->item;
+		return xstrdup(found->name);
+	} else {
+		return NULL;
 	}
-	return xstrdup_or_null(final_commit_name);
 }
 
 static char *prepare_initial(struct scoreboard *sb)