perf: make `hg perfwrite` more flexible The more flexible command was used recently while finding a solution for a buffering bug (eventually fixed in f9734b2d59cc (the changeset description uses a different benchmark)). In comparison to the previous version, the new version is much more flexible. While using it, the focus was on testing small writes. For this reason, by default it calls ui.write() 100 times with a single byte plus one newline byte, for 100 lines. To get the previous behavior, run `hg perfwrite --nlines=100000 --nitems=1 --item='Testing write performance' --batch-line`.

chg: fix typo

copies: implement __repr__ on branch_copies for debugging Differential Revision: https://phab.mercurial-scm.org/D8650

phases: remove useless lookup of repo[rev].rev() in _retractboundary changectx object is no longer needed thanks to a54ee130210a.

ui: replace `self._ferr` with identical `dest` Originally, it was part of a larger change that was abandoned. IMHO it makes the code slightly cleaner and saves one attribute access, so I decided to send it anyway instead of throwing it away.

absorb: make it clear what happens when no input Differential Revision: https://phab.mercurial-scm.org/D8643

tests: add hghave rule 'setprocname' to check if osutil.setprocname and use it setprocname is not present when we build a pure version. This leads to output changes in test-chg.t This should make test suite green on Python 2 pure build with chg. Differential Revision: https://phab.mercurial-scm.org/D8638

util: flush stderr explicitly after using warnings.warn() Due to some unknown reasons, when using chg with python3, the warnings.warn() output is not flushed. Fixes test-devel-warnings.t on py3 with chg.

phases: improve performance of _retractboundary The old version repeatedly converts nodes to revisions, which is a moderately expensive operation. Mapping all new changes once to revisions and back at the end reduces the time spend in _retractboundary during the unbundling of NetBSD's src from 67s to 17s. Differential Revision: https://phab.mercurial-scm.org/D8641

tests: use proctutil.stdout.write() instead of print() in test-extension.t I was debugging this test failure on python3 + chg. I get the following hunk as test failure: ``` @@ -206,6 +206,18 @@ Check normal command's load order of ext 4) bar uipopulate 5) foo reposetup 5) bar reposetup + 4) foo uipopulate (chg !) + 4) bar uipopulate (chg !) + 4) foo uipopulate (chg !) + 4) bar uipopulate (chg !) + 4) foo uipopulate (chg !) + 4) bar uipopulate (chg !) + 4) foo uipopulate (chg !) + 4) bar uipopulate (chg !) + 4) foo uipopulate (chg !) + 4) bar uipopulate (chg !) + 5) foo reposetup (chg !) + 5) bar reposetup (chg !) 0:c24b9ac61126 ``` After hours of debugging and head scracthing, I figured out that something is wrong with output flushing. I initially switched the print() statements to ui.warn() but thanks to Yuya who suggested using procutil.stdout.write() instead.

fuzz: tell manifest fuzzer about longer node hashes Differential Revision: https://phab.mercurial-scm.org/D8374

absorb: preserve changesets which were already empty Most commands in Mercurial (commit, rebase, absorb itself) don’t create empty changesets or drop them if they become empty. If there’s a changeset that’s empty, it must be a deliberate choice of the user. At least it shouldn’t be absorb’s responsibility to prune them. The fact that changesets that became empty during absorb are pruned, is unaffected by this. This case was found while writing patches which make it possible to configure absorb and rebase to not drop empty changesets. Even without having such config set, I think it’s valuable to preserve changesets which were already empty.

absorb: preserve branch-closing changesets even if empty This makes the behavior consistent with 'hg commit', which allows to create otherwise empty changesets if they close the branch. A lost branch closure can inadvertently re-open a branch, so it should be preserved.

absorb: preserve branch-changing changesets even if empty This makes the behavior consistent with 'hg commit', which allows to create otherwise empty changesets if the branch changes compared to the parent. A branch change can denote important information, so it should be preserved.

rhg: add Command trait for subcommands implemented by rhg Normalizes the interface of the cli's commands Differential Revision: https://phab.mercurial-scm.org/D8611 Differential Revision: https://phab.mercurial-scm.org/D8648

rhg: add rhg crate The goal of rhg is to speedup some of hg's commands when possible by bypassing python entirely for the time being. It is by no means a replacement for hg as it will not support extentions or configuration and implement only a subset of hg's commands and options. Only use rhg if you understand what the tradeoffs are. Differential Revision: https://phab.mercurial-scm.org/D8610