py3: add a r'' to prevent transformer adding b''

py3: add a r'' to prevent transformer adding b''

# skip-blame because just r'' prefix

Differential Revision: https://phab.mercurial-scm.org/D6377

--- a/mercurial/commands.py	Mon May 06 22:51:10 2019 +0200
+++ b/mercurial/commands.py	Wed May 15 20:37:39 2019 +0300
@@ -4680,7 +4680,7 @@
     """
     ret = repo.recover()
     if ret:
-        if opts['verify']:
+        if opts[r'verify']:
             return hg.verify(repo)
         else:
             msg = _("(verify step skipped, run  `hg verify` to check your "