rust-parsers: use in-place mutation instead of allocating a new `Vec` This is not done for the `dirstate-tree` feature, since it lacks `iter_mut`. Differential Revision: https://phab.mercurial-scm.org/D9136

revlog: pre-compute null revlog item for pure version The dynamically created tuple shows up in memory profiles and the use of nullid prevents the normal constant building to work. Differential Revision: https://phab.mercurial-scm.org/D9154

packaging: normalize - to _ in WiX Id values - is not a valid identifier character in WiX Ids. So let's normalize accordingly. I discovered this issue after a subsequent change which introduces a directory with a - in its name. Differential Revision: https://phab.mercurial-scm.org/D9147

contrib: install Rust 1.46.0 Let's use the latest/greatest version of Rust in the automation environment. Differential Revision: https://phab.mercurial-scm.org/D9146

contrib: install latest versions of Python Let's keep our build environment modern. We upgrade 3.5-3.8 on Linux. Just 3.7 and 3.8 on Windows because we don't use <3.7 on Windows. Differential Revision: https://phab.mercurial-scm.org/D9145

help: extract logic for listing commands and topics Differential Revision: https://phab.mercurial-scm.org/D9134

copies: directly pass a changes object to the copy tracing code The object contains all the data we need. For example, the `is_merged` callback can now use the associated precomputed data. This will be useful again soon when the `salvaged` set will be introduce to solve the issue with delete file reverted during a merge. See 4b582a93316a and 14be07d5603c for details. Differential Revision: https://phab.mercurial-scm.org/D9117

copies: no longer change the sidedata flag With the new sidedata storage that include data about all file changes, every revision has one, so the sidedata flag is not longer a good way to spot changeset with copy information. So we drop this check to simplify the code We optimisation itself provided an interesting speedup, so we will likely reintroduce something similar, with a dedicated flag, in the future. Differential Revision: https://phab.mercurial-scm.org/D9116

copies: use dedicated `_revinfo_getter` function and call We want to return data in a different form, so we need different revinfo function. At that point it make sense to have different getter. Differential Revision: https://phab.mercurial-scm.org/D9115

copies: make two version of the changeset centric algorithm They are two main ways to run the changeset-centric copy-tracing algorithm. One fed from data stored in side-data and still in development, and one based on data stored in extra (with a "compatibility" mode). The `extra` based is used in production at Google, but still experimental in code. It is mostly unsuitable for other users because it affects the hash. The side-data based storage and algorithm have been evolving to store more data, cover more cases (mostly around merge, that Google do not really care about) and use lower level storage for efficiency. All this changes make is increasingly hard to maintain de common code base, without impacting code complexity and performance. For example, the compatibility mode requires to keep things at different level than what we need for side-data. So, I am duplicating the involved functions. The newly added `_extra` variants will be kept as today, while I will do some deeper rework of the side data versions. Long terms, the side-data version should be more featureful and performant than the extra based version, so I expect the duplicated `_extra` functions to eventually get dropped. Differential Revision: https://phab.mercurial-scm.org/D9114