procutil: assign pseudo file object if sys.stdout/stderr is missing
This basically simulates the Python 2 behavior. If libc stdio were used,
these file objects would be available and raise EBADF. There is subtle
difference between py2 and py3, but I think py3 behavior (i.e. exit 255)
is more correct.
"if" conditions are adjust so that they look similar to
dispatch.initstdio().
{
"conduit_uri": "https://phab.mercurial-scm.org/api",
"phabricator.uri": "https://phab.mercurial-scm.org/",
"repository.callsign": "HG",
"arc.land.onto.default": "@",
"base": "hg:.^"
}