httppeer: explicitly catch urlerr.httperror and re-raise
On Python 3 it seems urllib.error.HTTPError doesn't set the .args
field of the exception to have any contents, which then breaks our
socket.error catch. This works around that issue.
Differential Revision: https://phab.mercurial-scm.org/D2448
{
"conduit_uri": "https://phab.mercurial-scm.org/api",
"repository.callsign": "HG",
"arc.land.onto.default": "@",
"base": "hg:.^"
}