- * to cancel incoming transfers (eg. if there is a local error),
- * but they MUST then call reply_with_*.
+ * to cancel incoming transfers (eg. if there is a local error).
+ *
+ * If and only if this function does NOT return -2, they MUST then
+ * call reply_with_*
+ * (see https://bugzilla.redhat.com/show_bug.cgi?id=576879#c5).