salut_file_transfer_channel_close: don't cancel if the channel was already cancelled
salut_file_transfer_channel_close: don't cancel if the channel was already cancelled

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