dirstate: no longer pass the `oldstate` value to the dirstatemap The dirstatemap already have this information. Differential Revision: https://phab.mercurial-scm.org/D10966

dirstate: stop using `oldstate` in `dirstate._addpath` We don't need to pass the oldstate around, so lets use the new property instead. Differential Revision: https://phab.mercurial-scm.org/D10965

dirstate: drop the now unused magic constants for the dirstate module We no longer need them for the dirstate logic. We only need them in the dirstate map (and parsers) logic. This smell like progress. Differential Revision: https://phab.mercurial-scm.org/D10964

dirstate: move the handling of special case within the dirstatemap The dirstatemap is as well, if not better, suited to decided how to encode the various case. So we move the associated code in the dirstatemap `addfile` method. This means the dirstate no longer need to know about the various magic value used in the dirstate V1 format. The pain of the messy API start to be quite palpable in Rust, we should clean this up once the current large refactoring is dealt with. Differential Revision: https://phab.mercurial-scm.org/D10963

rust: bump rust-cpython version for 0.6.0 That function as a nice `is_none` method on `PyObject` that we will put to use. Differential Revision: https://phab.mercurial-scm.org/D10962

rust-dirstate: make the MTIME_UNSET public We will use it in the cpython layer soon. Differential Revision: https://phab.mercurial-scm.org/D10961