node: introduce nodeconstants class In preparing for moving from SHA1 hashes to a modern hash function, place nullid and other constant magic vules in a class. Provide the active set of constants in the repository and push it down. Provide nullid directly in strategic places like the repository as it is accessed very often. This changeset introduces the API change, but not the mechanical replacement of the node.py attributes itself. Differential Revision: https://phab.mercurial-scm.org/D9750

revlog: guarantee that p1 != null if a non-null parent exists This change does not affect the hashing (which already did this transformation), but can change the log output in the rare case where this behavior was observed in repositories. The change can simplify iteration code where regular changesets and merges are distinct branches. Differential Revision: https://phab.mercurial-scm.org/D10150

push: allow to specify multiple destinations I end up needing that on a regular basis and it turn out to be very simple to implement. See documentation and test for details. Differential Revision: https://phab.mercurial-scm.org/D10161

push: indent the some part of the command That code will be put in a loop in the next changeset, pre-indenting make the next change clearer. Differential Revision: https://phab.mercurial-scm.org/D10160

bundle: optional multithreaded compression, ATM zstd-only Compression type can be a huge chunk of "hg bundle", especially when using the higher compression levels. With level=22 and threads=7, the NetBSD test repository took 28:39 wall time and 157:47 user time. Before, level=22 would take 129:20 wall time and 129:07 user time. Differential Revision: https://phab.mercurial-scm.org/D9283

rust: Preallocate the returned `Vec` in `utils::files::relativize_path` Profiling `rhg files > /dev/null` on an old snapshot of mozilla-central (with `perf` and the Firefox Profiler: https://github.com/firefox-devtools/profiler/blob/main/docs-user/guide-perf-profiling.md) showed non-trivial time spend in this function and in `realloc`. This change makes the wall-clock time for that process on my machine go from ~190 ms to ~150 ms. Differential Revision: https://phab.mercurial-scm.org/D10199

black: merge config into main pyproject.toml now that we have it This means that naive contributors who just run `black` on a source file will get reasonable behavior as long as they have a recent black. Yay! This was previously D9834 but was rolled back due to test failures. nbjoerg thinks it's time to try again, so let's give it a shot. Differential Revision: https://phab.mercurial-scm.org/D10185

pyproject: add config file This will tell pip et al to call our setup.py for the majority of packaging concerns, but also gives us a place to put standard config stuff like black. This was previously D9833, but was rolled back due to test breakage. nbjoerg thinks that breakage is now resolved, so we're trying again. Differential Revision: https://phab.mercurial-scm.org/D10184

perf-util: add an helper revset to use the same spec as the case search script This make result of the searcher script easier to use. Differential Revision: https://phab.mercurial-scm.org/D10228

perf-helpers: add a search-discovery-case script This a small script I built to look for interesting discovery case. It is fairly basic but could be useful in various situation so lets put it in the main repositories. Differential Revision: https://phab.mercurial-scm.org/D10225