D1238: overlayworkingctx: add _manifest, files(), added(), removed(), modified()

[phillco (Phil Cohen)]

phillco added inline comments.

INLINE COMMENTS

> phillco wrote in context.py:2022
> Oops, I think it should be and it got lost along the way. BUT LT ME CONFIRM.

*but let me confirm

REPOSITORY
  rHG Mercurial

REVISION DETAIL
  https://phab.mercurial-scm.org/D1238

To: phillco, #hg-reviewers, durin42
Cc: mercurial-devel