dirstate-v2: reorder flag to group related one together Since the format is not frozen yet, it seems like the right moment to do it. Differential Revision: https://phab.mercurial-scm.org/D11704

dirstate-v2: read the fallback value in Rust This was overlooked in a previous commit. Differential Revision: https://phab.mercurial-scm.org/D11695

dirstate-v2: adjust the meaning of directory flags Tracking directory "explicitly" give use the opportunity to distinct between entry that are untracked because they are part of the directory structure and entry that are ignored/unknown files on the files system. The help is adjusted to the new semantic and the code now comply to it for both read and write. Differential Revision: https://phab.mercurial-scm.org/D11694

dirstate-v2: actually use sub-second mtime precision Instead of zero, set the nanoseconds field to its correct value whenever possible and preserve it across serialization+parsing. Differential Revision: https://phab.mercurial-scm.org/D11702

dirstate: ignore sub-second component when either is zero in mtime When comparing mtimes for equality. Some APIs simply return zero when more precision is not available. When comparing values from different sources, if only one is truncated in that way, doing a simple comparison would cause many false negatives. Differential Revision: https://phab.mercurial-scm.org/D11701

dirstate-v2: add a new MTIME_SECOND_AMBIGUOUS flags This flag will let us use more `mtime` value in the future. For now we have a minimal handling of the flag at read time, but we will never put ourself in a situation where we will needs to writes it. See the flag documentation for details. Differential Revision: https://phab.mercurial-scm.org/D11700

dirstate: store mtimes with nanosecond precision in memory Keep integer seconds since the Unix epoch, together with integer nanoseconds in the `0 <= n < 1e9` range. For now, nanoseconds are still always zero. This commit is about data structure changes. Differential Revision: https://phab.mercurial-scm.org/D11684

rust: remove now-unused DirstateEntry::clear_ambiguous_mtime method Differential Revision: https://phab.mercurial-scm.org/D11696

dirstate: align Rust function name to `need_delay` The rest of the code use this name. It is not a great name, but it is better to stay consistent. Differential Revision: https://phab.mercurial-scm.org/D11699

dirstate: rename a `very_likely_equal` method to `likely_equal` No need to oversell it. Differential Revision: https://phab.mercurial-scm.org/D11691