How to depend on a variant (or do I want subports)?

[Jeremy Lavergne]

> Which is very unwanted on the other hand, since it is so sticky, i.e. will have to be increased forever once it has been added to a port file, right?!
> So, it's best to find a way around epoch!

Apart from reinstalling very large packages, are there reasons to avoid rebuilding on any change rather than just checking epoch_version_revision?

If it should be more manual perhaps a commit hook that incremented a set variable to provide a linear change count. I'm thinking if it must be linear, perhaps revision can be made into this: version is human-readable while revision is for port to determine if a change has occurred.

If it doesn't need to be linear then we could just use a hash of the Portfile to track if anything changed. Anything at all.