Using `:latest` tag is typically a cause of pain, as underlying image
changes behavior. Here, I'm switching to using a point release, and
re-updating the stored tarballs with it.
Sadly, when saving/loading images, the repo digeset is not supported:
https://github.com/moby/moby/issues/22011 ; but using point releases
should mitigate the problem.
The motivation here is that docker tests have some flakiness due to
accidental importing of `busybox:latest` which has `/bin/nc` that no
longer supports `-p 0`:
```
$ docker run -it --rm busybox /bin/nc -l 127.0.0.1 -p 0
Unable to find image 'busybox:latest' locally
latest: Pulling from library/busybox
Digest: sha256:2a03a6059f21e150ae84b0973863609494aad70f0a80eaeb64bddd8d92465812
Status: Downloaded newer image for busybox:latest
nc: bad local port '0'
```
Looks like older busybox versions (e.g. `busybox:1.24` do honor `-p 0`
as the test expect, but I would rather update busybox to fix.
6b216a6015