`opensafely pull` returns a seemingly unnecessary (warning?) message about an invalid reference format

I don't know how long this has been there but I see this on the bottom line of opensafely pull output: invalid reference format, e.g.,

% opensafely pull
Updating OpenSAFELY ehrql:v1 image
v1: Pulling from opensafely-core/ehrql
Digest: sha256:33b638bb7f853639966886e0a9c9ac2e234f0b2b33be365f0a91fdfa0497f455
Status: Image is up to date for ghcr.io/opensafely-core/ehrql:v1
ghcr.io/opensafely-core/ehrql:v1

What's Next?
  View a summary of image vulnerabilities and recommendations → docker scout quickview ghcr.io/opensafely-core/ehrql:v1
Updating OpenSAFELY ehrql:<none> image
invalid reference format

I can obtain the same message seemingly about the chortextractor and r images. Maybe the message refers to the last image updated on a user's system, or something like that (I didn't trace it).

If you need it

% opensafely --version
opensafely v1.41.2

It's not clear to me what this message means but I'd say it doesn't seem necessary to report this to the user.

Reproduce the output with opensafely v1.41.2 using the opensafely pull entry point, and inspect how it handles the ehrql: image update and Docker image references. Trace the source of invalid reference format; done means valid images still update and the command no longer reports a misleading error for an absent image reference.