Reset the preferred private JID when all resources leave a room

For example if we are talking in private with nick Joe from
room #foo, and then we leave that room, we start receiving Joe’s
message from the server-wide JID

e2e tests included!!!

src/bridge/bridge.cpp

@@ -344,7 +344,12 @@ void Bridge::leave_irc_channel(Iid&& iid, std::string&& status_message, const st
 
   const auto resources = this->number_of_resources_in_chan(key);
   if (resources == 1)
-    irc->send_part_command(iid.get_local(), status_message);
+    {
+      irc->send_part_command(iid.get_local(), status_message);
+      // Since there are no resources left in that channel, we don't
+      // want to receive private messages using this room's JID
+      this->remove_all_preferred_from_jid_of_room(iid.get_local());
+    }
   else
     {
       IrcChannel* chan = irc->get_channel(iid.get_local());
@@ -767,6 +772,18 @@ void Bridge::remove_preferred_from_jid(const std::string& nick)
     this->preferred_user_from.erase(it);
 }
 
+void Bridge::remove_all_preferred_from_jid_of_room(const std::string& channel_name)
+{
+  for (auto it = this->preferred_user_from.begin(); it != this->preferred_user_from.end();)
+    {
+      Iid iid(Jid(it->second).local);
+      if (iid.get_local() == channel_name)
+        it = this->preferred_user_from.erase(it);
+      else
+        ++it;
+    }
+}
+
 void Bridge::add_waiting_irc(irc_responder_callback_t&& callback)
 {
   this->waiting_irc.emplace_back(std::move(callback));

src/bridge/bridge.hpp

@@ -185,6 +185,11 @@ public:
    * Remove the preferred jid for the given IRC nick
    */
   void remove_preferred_from_jid(const std::string& nick);
+  /**
+   * Given a channel_name, remove all preferred from_jid that come
+   * from this chan.
+   */
+  void remove_all_preferred_from_jid_of_room(const std::string& channel_name);
   /**
    * Add a callback to the waiting list of irc callbacks.
    */