D7503: rust-dirs: address failing tests for `dirs` impl with a temporary fix

[Alphare (Raphaël Gomès)]

Alphare added a comment.


  > I generally prefer adding safety checks at ABI boundary. If malicious input
  > makes Rust code crash or exhaust CPU/memory resource, I would add sanity
  > check to rust-cpython layer.
  
  Sure, that makes sense in our configuration, but we need to consider `hg-core` as its own standalone library when making decisions like this. Either the `Dirs` / `dirs` API has changed to this new behavior (which I'm not super happy about), either we revert the changes proposed by Augie with a change in the fuzzer instead.
  
  Sorry for the warnings, I'll send a follow-up, I've been caught up in another project.

REPOSITORY
  rHG Mercurial

CHANGES SINCE LAST ACTION
  https://phab.mercurial-scm.org/D7503/new/

REVISION DETAIL
  https://phab.mercurial-scm.org/D7503

To: Alphare, #hg-reviewers
Cc: yuja, marmoute, durin42, kevincox, mercurial-devel