.arcconfig

phabricator: add a config to use curl for communication

Not sure why, but I got `phabsend` hang on work network pretty frequently.
The traceback indicates it hangs at `_sslobj.do_handshake()`:

  File "mercurial/sslutil.py", line 404, in wrapsocket
    sslsocket = sslcontext.wrap_socket(sock, server_hostname=serverhostname)
  File "/usr/lib/python2.7/ssl.py", line 363, in wrap_socket
    _context=self)
  File "/usr/lib/python2.7/ssl.py", line 611, in __init__
    self.do_handshake()
  File "/usr/lib/python2.7/ssl.py", line 840, in do_handshake
    self._sslobj.do_handshake()

I had tried adding `timeout` in various places but they seem not effective.
It seems easier to just allow shelling out to `curl` with retry and timeout
flags.

This could also be helpful for people with an older Python installed without
modern security (SNI).

Differential Revision: https://phab.mercurial-scm.org/D605

{
    "conduit_uri": "https://phab.mercurial-scm.org/api",
    "repository.callsign": "HG",
    "arc.land.onto.default": "@",
    "base": "hg:.^"
}