Warn on no-revbump for PEP517

[thesamesam]

Enabling PEP517 mode is a non-conservative change and may result in installed files changing. It should always be done in a new revision.

[thesamesam]

We need to handle this before too much of the tree is converted to PEP517, as it'll stop being useful then.

[arthurzam]

Currently the issue is that in the git checks, we use the not-parsed ebuilds, which results in my inability to know the state of PEP517. This is the reason for it being postponed.

[thesamesam]

I think we can do it with reduced accuracy if we regex-match the text for ^DISTUTILS_USE_PEP517 either having a changed value on the match on the right-hand-side of = or just not existing/existing in the changed ebuild (like we do for the copyright check in feed()) but I'm not sure how to get the old ebuild text.

[arthurzam]

but I'm not sure how to get the old ebuild text.

pkgcheck/src/pkgcheck/checks/git.py

Lines 364 to 376 in 861c24a

	if pkg not in added and old_pkg.rdepend != new_pkg.rdepend:
	yield RdependChange(pkg=new_pkg)
	old_slot, new_slot = old_pkg.slot, new_pkg.slot
	if old_slot != new_slot:
	slotmoves = (
	x[1:] for x in self.repo.config.updates.get(new_pkg.key, ()) if x[0] == "slotmove"
	)
	for atom, moved_slot in slotmoves:
	if atom.match(old_pkg) and new_slot == moved_slot:
	break
	else:
	yield MissingSlotmove(old_slot, new_slot, pkg=new_pkg)