D651: blackbox: remove _bbvfs state

[durham (Durham Goode)]

durham added inline comments.

INLINE COMMENTS

> blackbox.py:100
> +            if repo:
> +                return repo.vfs
> +

I'd probably explicitly return None instead of relying on the implicit return value.

REPOSITORY
  rHG Mercurial

REVISION DETAIL
  https://phab.mercurial-scm.org/D651

To: quark, #hg-reviewers, durham
Cc: mercurial-devel