D1791: tests: make autodiff.py work on Python 3

[durin42 (Augie Fackler)]

durin42 added a comment.


  For patches like this that are just adding bytes prefixes, let's go ahead and do a '# skip-blame' as in https://phab.mercurial-scm.org/rHGd92dc725223bbde09963fc431e57d32a40c4167d (aka https://phab.mercurial-scm.org/D1170) so that blame is cleaner in the future.

REPOSITORY
  rHG Mercurial

REVISION DETAIL
  https://phab.mercurial-scm.org/D1791

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