during the profile connection workflow, joined rooms are retrieved, then presence are
filled, all asynchronously. In some cases, all rooms may not be joined when presence are
filled, resulting in cache being already filled with a `nick` when cache is set for the
room itself. Because of that, a `nick` may be displayed in contact list instead of MUC local
part. This patch fixes it by removing `nick` if it exists when cache a MUC room.
fix 305
fa50789710