Diff

--- a/plugins/muc/history.lib.lua	Mon May 07 22:12:22 2018 +0200
+++ b/plugins/muc/history.lib.lua	Mon May 07 22:10:29 2018 +0200
@@ -156,12 +156,15 @@
 -- Have a single muc-add-history event, so that plugins can mark it
 -- as handled without stopping other muc-broadcast-message handlers
 module:hook("muc-broadcast-message", function(event)
-	local historic = event.stanza:get_child("body");
-	if historic then
+	if module:fire_event("muc-message-is-historic", event) then
 		module:fire_event("muc-add-history", event);
 	end
 end);
 
+module:hook("muc-message-is-historic", function (event)
+	return event.stanza:get_child("body");
+end, -1);
+
 return {
 	set_max_length = set_max_history_length;
 	parse_history = parse_history;