[mod_loopback] clear confirm properties from a-leg

src/mod/endpoints/mod_loopback/mod_loopback.c

@@ -316,6 +316,8 @@ static switch_status_t channel_on_init(switch_core_session_t *session)
 				switch_channel_set_variable(tech_pvt->other_channel, h->name, h->value);
 			}
 
+			switch_channel_del_variable_prefix(channel, "group_confirm_");
+
 			switch_event_destroy(&vars);
 		}