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

rust-status: collect traversed directories if required Some commands (`hg purge` notably) register the `traversedir` callback on their matcher to run said callback every time a directory is traversed. This is the first of three patches, further broadening Rust support for status. Unfortunately, there is no way around collecting a full `Vec` (or any other owned datastructure, like a radix tree) and pushing it back up the Python layer since keeping the Python callback in a closure would mean giving up multithreading because of the GIL, which is obviously unacceptable. Performance is still a lot better than the Python+C path. 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/D8518

rust-status: don't dispatch unknown file when traversing if not listing unknowns This usually isn't a (functional) problem since we ignore the unknown files anyway, but when specifically using `hg purge`, unknown files were iterated over regardless of the option being true. This is both more correct and more efficient. Differential Revision: https://phab.mercurial-scm.org/D8517

status: update comment to reflect the more recent situation This is a gratuitous cleanup. Differential Revision: https://phab.mercurial-scm.org/D8516

hooks: provide access to transaction changes for internal hooks External hooks are skipped here as the environment often has a size limit in the low MBs and that can easily be reached by larger transactions. Differential Revision: https://phab.mercurial-scm.org/D8490