How to compare against earlier, non-published git revision

[nafg]

For instance, suppose I want to generate a report on a PR to know what API changes it introduced, relative to its merge base.

I can think of two approaches:

1. A script that first checks out the merge base commit, runs sbt publishLocal and records the version (hopefully using sbt-dynver or some other way to ensure that the version is different than the version after the PR -- or does it matter?), then checks out the PR (or a merge commit with it) and runs MiMa using the previously recorded version to specify the artifacts to compare against
2. Resolve the artifacts on the fly from https:/jitpack.io, using the git revision as the artifact version.

Is there a better way?

P.S. is there a better place to ask questions?