salut_muc_channel_close: raise an error if the channel is already closed
salut_muc_channel_close: raise an error if the channel is already closed

freedesktop-unofficial-mirror/telepathy__telepathy-salut,freedesktop-unofficial-mirror/telepathy__telepathy-salut,freedesktop-unofficial-mirror/telepathy__telepathy-salut,freedesktop-unofficial-mirror/telepathy__telepathy-salut