grep: improve test coverage Differential Revision: https://phab.mercurial-scm.org/D8542

phabricator: avoid passing None to pycompat.fsdecode Differential Revision: https://phab.mercurial-scm.org/D8525

setup: stop asking cargo to spam It prints this kind of stuff by default: Compiling regex v1.3.6 Compiling rand v0.7.3 Compiling crossbeam-deque v0.7.3 which is way better than we ask for before this change, which is screen after screen of compilation commands and irrelevant warnings in crates we use. Differential Revision: https://phab.mercurial-scm.org/D8537

git: implement some changelog methods Differential Revision: https://phab.mercurial-scm.org/D8540

git: avoid looking-up parents for the null commit Differential Revision: https://phab.mercurial-scm.org/D8541

git: fix probable missing return Differential Revision: https://phab.mercurial-scm.org/D8539

rust: fix warning about unnecessary mut If there's a reason to use mut (like compability with older compilers), then we should stick `#[allow(unused_mut)]` on the declaration. Differential Revision: https://phab.mercurial-scm.org/D8538

upgrade: support upgrade and downgrade from persistent nodemap The requirements is now recognised and dealt with and the associated files properly handled. The persistent nodemap should be ready for usage in the field now. Differential Revision: https://phab.mercurial-scm.org/D8431

status: also support for `traversedir` callback in the Rust fast-path Repeating the performance numbers from the `hg-core` change: Running `hg clean/purge` on Netbeans' repo (100k files): ``` | No-op | 30% unknown -------------------------- Rust | 1.0s | 1.67s C | 2.0s | 2.87s ``` Differential Revision: https://phab.mercurial-scm.org/D8520

rust-hg-cpython: update status bridge with the new `traversedir` support Differential Revision: https://phab.mercurial-scm.org/D8519