D1211: context: switch ctx() use to changectx()

[phillco (Phil Cohen)]

phillco added a subscriber: sid0.
phillco added a comment.


  cc @sid0 on the absentfilectx thing, maybe he knows more

REPOSITORY
  rHG Mercurial

REVISION DETAIL
  https://phab.mercurial-scm.org/D1211

To: phillco, #hg-reviewers, dlax
Cc: sid0, martinvonz, mercurial-devel