gibber_unix_transport_dispose: set wait_creds_cb to NULL so callback won't be called when we are disposing
gibber_unix_transport_dispose: set wait_creds_cb to NULL so callback won't be called when we are disposing

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