- * Otherwise, return a negative value. If extras is non-NULL, it is a
- * list of additional refnames with which refname is not allowed to
- * conflict. If skip is non-NULL, ignore potential conflicts with refs
- * in skip (e.g., because they are scheduled for deletion in the same
- * operation). Behavior is undefined if the same name is listed in
- * both extras and skip.
+ * Otherwise, return a negative value and write an explanation to err.
+ * If extras is non-NULL, it is a list of additional refnames with
+ * which refname is not allowed to conflict. If skip is non-NULL,
+ * ignore potential conflicts with refs in skip (e.g., because they
+ * are scheduled for deletion in the same operation). Behavior is
+ * undefined if the same name is listed in both extras and skip.