D1285: repoview: add a new attribute _visibilityexceptions and related API

[quark (Jun Wu)]

quark added inline comments.

INLINE COMMENTS

> yuja wrote in localrepo.py:575
> raise ProgrammingError?

I guess `hg log -r HASH --hidden` would go through this code path so `pass` makes sense.

REPOSITORY
  rHG Mercurial

REVISION DETAIL
  https://phab.mercurial-scm.org/D1285

To: pulkit, #hg-reviewers, quark, yuja
Cc: yuja, lothiraldan, quark, mercurial-devel