Mender-convert tag 4.0.1 -> MENDER ARTIFACT VERSION master?

Isn’t this a bug, that you forgot to pin
MENDER_ARTIFACT_VERSION to a particular tag.
https://github.com/mendersoftware/mender-convert/blob/4.0.1/Dockerfile#L14

master is a moving target and not good.

What should I use for MENDER_ARTIFACT_VERSION, when running mender-convert in tag 4.0.1?
Thanks.