for (node = thread->message_list->head; node; node = node->next) {
message = node->message;
in_reply_to = _notmuch_message_get_in_reply_to (message);
- if (in_reply_to && strlen (in_reply_to) &&
+ /*
+ * if we reach the end of the list without finding a top-level
+ * message, that means the thread is a cycle (or set of
+ * cycles) and any message can be considered top-level
+ */
+ if ((thread->toplevel_list->head || node->next) &&
+ in_reply_to && strlen (in_reply_to) &&
g_hash_table_lookup_extended (thread->message_hash,
in_reply_to, NULL,
(void **) &parent))