rhg: fallback if the current command has any generic hook defined We do not handle hooks yet. Differential Revision: https://phab.mercurial-scm.org/D11380

rhg-cat: fallback in presence of a fileset These are unsupported so far. Differential Revision: https://phab.mercurial-scm.org/D11379

rhg-cat: fallback when detecting `.` or `..` path segments We do not normalize paths correctly yet, so exclude the shortcuts. Differential Revision: https://phab.mercurial-scm.org/D11378

rhg: add support for calling `rhg cat` without a revision Turns out the necessary pieces were there already. Like the Python implementation, we default to the first parent of the dirstate. Differential Revision: https://phab.mercurial-scm.org/D11377

branching: merge with stable

dirstate: Remove the Rust abstraction DirstateMapMethods This Rust trait used to exist in order to allow the DirstateMap class exposed to Python to be backed by either of two implementations: one similar to the Python implementation based on a "flat" `HashMap<HgPathBuf, DirstateEntry>`, and the newer one based on a tree of nodes matching the directory structure of tracked files. A boxed trait object was used with dynamic dispatch. With the flat implementation removed and only the tree one remaining, this abstraction is not useful anymore and the concrete type can be stored directly. It remains that the trait was implemented separately for `DirstateMap<'_>` (which takes a lifetime parameter) and `OwningDirstateMap` (whose job is to wrap the former and hide the lifetime parameter), with the latter impl only forwarding calls. This changeset also removes this forwarding. Instead, the methods formerly of the `DirstateMapMethods` trait are now inherent methods implemented for `OwningDirstateMap` (where they will actually be used) but in the module that defines `DirstateMap`. This unusual setup gives access to the private fields of `DirstateMap` from those methods. Differential Revision: https://phab.mercurial-scm.org/D11517