rust: use crossbeam-channel crate directly … instead of its reexport in the crossbeam crate. This removes two crates from the dependency graph. Differential Revision: https://phab.mercurial-scm.org/D9521

wireprotov2: re-add tuple around `bundle2` check I stumbled upon this while looking for the current (v1) `capable` method. It looks like 9c2c77c73f23 accidentally removed the comma, turning the tuple into a simple parenthesis expression. This has not been detected since wireproto2 is not in use AFAIK. Differential Revision: https://phab.mercurial-scm.org/D9518

upgrade: gather code about requirement checking together They just moved in the same file, now they are grouped together and documented. Differential Revision: https://phab.mercurial-scm.org/D9486

upgrade: extract the checking of target requirements change This logic is fairly independant, lets move it out of the main function. Differential Revision: https://phab.mercurial-scm.org/D9485

upgrade: drop an outdated comment We can control the added/removed requirement through config for multiple years. Differential Revision: https://phab.mercurial-scm.org/D9484

upgrade: gather code about source checking together They just moved in the same file, now they are grouped together and documented. Differential Revision: https://phab.mercurial-scm.org/D9483

upgrade: move requirements checking in a dedicated function This is a simple an isolated check that can go next to the associated code. Differential Revision: https://phab.mercurial-scm.org/D9482