D2038: py3: add r'' to convert keys to keyword arguments to str

[yuja (Yuya Nishihara)]

yuja added a comment.


  Queued, but perhaps we should stop using `**{...}` since we no longer
  need to support Python 2.5. `*args, opt=...` should work.
  
  https://docs.python.org/2/whatsnew/2.6.html#other-language-changes

REPOSITORY
  rHG Mercurial

REVISION DETAIL
  https://phab.mercurial-scm.org/D2038

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