[Bug]: ImageNameSubstitutor cannot set compatibility

[Fleshgrinder]

A custom ImageNameSubstitutor cannot be used to mark an image as compatible substitute for another image automatically, because all implementation I found call the compatibility assertion on their constructor argument, not on the image property from the parent class that actually applies the substitution.

I want to dynamically resolve images from a Dockerfile in the root of my project to allow Dependabot/Renovate to automatically update the images for me, and thus keep my tests up-to-date. For this I wanted to use short aliases and to set compatibility dynamically. However, this isn't possible for the reasons explained.

I'm filing this as a bug, because I believe that this isn't the intended behavior. Feel free to change this.