Merge with daurnimator

diff --cc plugins/muc/muc.lib.lua
index 8cf8d882e5895962a2a3e779267a52e9d6cc4e46,27c50cd48a74748473563f70dbd631772074b451..5debb4a36ada98541951e43ce976fd3878c5f432
--- 1/plugins/muc/muc.lib.lua
--- 2/plugins/muc/muc.lib.lua
+++ b/plugins/muc/muc.lib.lua
@@@ -1031,8 -1264,8 +1264,8 @@@ function room_mt:can_set_role(actor_jid
  
        if actor_jid == true then return true; end
  
-       local actor = self._occupants[self._jid_nick[actor_jid]];
+       local actor = self._occupants[self:get_occupant_jid(actor_jid)];
 -      if actor.role == "moderator" then
 +      if actor and actor.role == "moderator" then
                if occupant.affiliation ~= "owner" and occupant.affiliation ~= "admin" then
                        if actor.affiliation == "owner" or actor.affiliation == "admin" then
                                return true;