A way to mark some commits as "DO NOT MERGE"

[jyasskin]

It would be nice to have jj enforce that it won't publish certain changes. I have 2 kinds in my workflow:

1. work-in-progress where I expect to need to rewrite the marked change and all its descendants before I publish them
2. "make this work in my environment" changes/bookmarks (generally when I don't control upstream), where if I'm trying to publish a descendant bookmark, I want to rebase its branch onto main before publishing.

For both, I might still want to save the marked change to some remote repository, so I think my intuition is about ensuring either that particular bookmarks must never include the change, or that the change is never pushed to particular remotes.

[PhilipMetzger]

Are you aware of the git.private-commits setting? See https://www.jj-vcs.dev/latest/config/#set-of-private-commits