py3: hunt down str(exception) instances and use util.forcebytestr
I decided to grep around for \sstr\( and see what low-hanging fruit
that showed me. This was part of that hunt. That grep pattern still
has some things worth exploring.
Differential Revision: https://phab.mercurial-scm.org/D2440
{
"conduit_uri": "https://phab.mercurial-scm.org/api",
"repository.callsign": "HG",
"arc.land.onto.default": "@",
"base": "hg:.^"
}