merge: use merge.clean_update() when applicable We have had this higher-level function (higher than `merge.update()`, that is) for a while. Let's simply some callers by using it. I don't know why I didn't do this when I introduced the function. After this patch, there are no remaining callers that call `hg.updaterepo()` with `overwrite=True`. We'll clean that up soon. Differential Revision: https://phab.mercurial-scm.org/D9063

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rust-tests: add test to check if `Cargo.lock` is up-to-date An out-of-date `Cargo.lock` is the source of rebase conflicts, prevents a reproductible build, introduces desync between the series that introduces a change in dependencies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 This commit demonstrates that the test works, the next one fixes the currently out-of-date `Cargo.lock`.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

scmutil: introduce function to check whether repo uses treemanifest or not In an upcoming patch, I wanted to check whether current repo uses treemanifest or not. I looked for a function and found that at all places we manually check for the requirement in repo requirements. I guess having a dedicated function for that is much better. Differential Revision: https://phab.mercurial-scm.org/D8981

chg: make is possible to call by default an hg binary located next to chg When a single version of hg is in use and it's in the PATH, using chg is just a matter of calling chg. But when there are multiple installations of hg+chg around, and hg is referred to with an absolute path, using chg is more annoying because it requires both changing the invocation to hg to use chg, but also setting CHGHG. Currently, we set HGPATH when we build chg to remove the need to set CHGHG in the previous paragraph. But that means chg now hardcodes its installation path, which makes the installation not relocatable. Hence this proposal to make chg find ./hg relative to itself (as opposed to CHGHG=./hg which find hg relative to cwd). This only works on linux as written, but since it's opt-in, it sounds fine. Tested by hand, as I'm not sure how else to test this. Differential Revision: https://phab.mercurial-scm.org/D9006

phases: fix performance regression with Python 2 Unlike Python 3, xrange doesn't support efficient "in" and uses a linear time scan instead. Expand the condition to handle it fast. Differential Revision: https://phab.mercurial-scm.org/D9072

rebase: move check for unresolved conflicts into lower-level rebasenode() I want to add another call to `rebasenode()` and it's better to not have to duplicate the check. Differential Revision: https://phab.mercurial-scm.org/D9075

rebase: add dryrun property to rebaseruntime I want to be able to check the property in `rebaseruntime._rebasenode()`. Passing the value via the runtime is a convenient way. Differential Revision: https://phab.mercurial-scm.org/D9074

rebase: when collapsing, p1 == dest, so use the former only `dest` is the destination we're rebasing onto, which is always the same as `p1` when using `--collapse`. This lets us simplify a bit. Differential Revision: https://phab.mercurial-scm.org/D9073