Comment # 9 on bug 1174285 from Ignaz Forster

Confirming.

On a regular (successful) run transactional-update will call
* snapper create --print-number --userdata
"transactional-update-in-progress=yes"
* btrfs subvolume set-default ${BTRFS_ID} ${SNAPSHOT_DIR}
* snapper modify -u "transactional-update-in-progress=" ${SNAPSHOT_ID}

Setting the new default subvolume in the second step seems to cause the
snapshot entry in /.snapshots/grub-snapshot.cfg to disappear on the next
snapper call - but only on read-write systems.

Arvin, is this intentional behaviour?