rebase: teach in-memory rebase to not restart with on-disk rebase on conflict When in-memory rebase runs into conflicts, it redoes the whole rebase operation. This patch teaches it to instead discard just the current `overlayworkingctx` and redo that node on disk. I've tested this by enabling in-memory rebase by default and checking that there are no unexpected differences after this patch. The next step is to make it so that `hg rebase --continue` can use in-memory merge. Differential Revision: https://phab.mercurial-scm.org/D9076

rust: update Cargo.lock Differential Revision: https://phab.mercurial-scm.org/D9080

rust-tests: add test to check if `Cargo.lock` is up-to-date An out-of-date `Cargo.lock` is the source of rebase conflicts, prevents a reproductible build, introduces desync between the series that introduces a change in dependencies and the one that eventually commits the `Cargo.lock`, and is just a general annoyance. This commit demonstrates that the test works, the next one fixes the currently out-of-date `Cargo.lock`. Differential Revision: https://phab.mercurial-scm.org/D9079