Delta update fails with `loading delta base image "sha256:<UUID>": failed to get digest sha256:<UUID>`

[lmbarros]

A delta update fails with an error message like this:

loading delta base image "sha256:<UUID>": failed to get digest sha256:<UUID>: open /var/lib/docker/image/overlay2/imagedb/content/sha256/<UUID>: no such file or directory'

This error is triggered because the delta basis image is not found locally. Currently, it's not clear what can cause this to happen, as in normal operation the basis image is supposed to be present.