contrib: fix dirstatenonnormalcheck to work in Python 3
This is a redo of D1963 that has the added benefit of not breaking
Python 2. Oops.
# skip-blame because this is bytes prefixes and a s/iteritems/items/
Differential Revision: https://phab.mercurial-scm.org/D1970
{
"conduit_uri": "https://phab.mercurial-scm.org/api",
"repository.callsign": "HG",
"arc.land.onto.default": "@",
"base": "hg:.^"
}