What do you think about the following approach:
- Define a lit substitution %diff_plist that resolves to diff -u -w -I "<string>/" -I "<string>.:" -I "version" -.
- Update these flags in your downstream fork.
It's kinda cool because it'll allow us to test exactly what we want in the exact output that we normally expect ourselves to produce. Step 1 is a good thing to do anyway because it reduces duplication.