Soo....with "proper lockfiles", it's desirable for us to keep using

--constraints

, rather than the current plan to use

pex -r lockfile.txt --no-transitive

. A major motivation is that it allows us to handle the problem of when it's not safe to use

[python-setup].resolve_all_constraints

and the repository PEX feature. For example, w/ a

pex_binary

using

platforms

, the subset of reqs might be valid, but the superset of all your reqs might include deps without wheels, so the superset fails to resolve. This was a real problem hit this month and now fixed to not use repository PEXes when platforms are used. But, we do still want to use a constraints file to lock down all versions I've been claiming constraints files can't be used because a) they don't support extras like

requests[security]

and b) they don't handle URL requirements. a) is an invalid reason, the lockfile should already have expanded

[security]

. b) was true, but is fixed by Pip 21.1 Only gotcha: Pip 21 dropped support for Python 2. Iiuc, this would mean that Pants 2.7+ no longer works with Python 2, which may be reasonable given that pip and rest of Python ecosystem has dropped support a while ago?