rust-dirstatemap: add `NonNormalEntries` class
This fix introduces the same encapsulation as the `copymap`. There is no easy way of doing this any better for now. `hg up -r null && time HGRCPATH= HGMODULEPOLICY=rust+c hg up tip` on Mozilla Central, (not super recent, but it doesn't matter): Before: 7:44,08 total After: 1:03,23 total Pretty brutal regression! This is a graft on stable of cf1f8660e568