Comment 16 for bug 1841137

This has bothered me for a long time
and lsof/fuser find nothing

```sh
$ sudo losetup -d /dev/loop38

$ losetup -l | grep del
/dev/loop38 0 0 1 1 /var/lib/snapd/snaps/snapd_19122.snap (deleted) 0 512
```

After tried several times of those cmds, the loop dev finally released

```sh
$ sudo systemctl stop *snap*
$ sudo systemctl start snapd.service
```

It's on
- ubuntu 22.04.2
- kernel 5.19.0-41-generic
- snapd 2.58+22.04