salt: 2018.3 regression - unable to create Caller in a runner

Description of Issue/Question

Runners which create salt.client.Caller throw exception listed below. This stops us from upgrading to 2018.3 release.

Steps to Reproduce Issue

On a CentOS 7.4 minimally installed VM, do the following -

# curl -o bootstrap-salt.sh -L https://bootstrap.saltstack.com
# sudo sh bootstrap-salt.sh -M git 2018.3

Make sure that following returns true -

[root@base2 ~]# salt-call test.ping
local:
    True

Now create a test runner with the following - cat /srv/_runners/test_runner.py

# -*- coding: utf-8 -*-
'''
test_runner.py - implementation of test runner api
Custom salt runner module
'''

import logging
import salt.client

__virtualname__ = 'test_runner'

#pylint: disable=bad-indentation, line-too-long, invalid-name

def __virtual__():
  return __virtualname__

def _get_logger():
  '''
  Get current logger.
  '''
  logger = logging.getLogger(__name__)
  return logger

def ping():
  '''
  Verify presence and installation of the module
  CLI Example:
     salt-run test_runner.ping
  '''
  local = salt.client.Caller()
  _get_logger().info('%s pinged', __name__)
  return True

Running (after configuring runners etc.) the salt-run test_runner.ping returns the following exception -

2018-04-05 12:41:06,259 [tornado.application:611 ][ERROR   ][9823] Exception in callback <functools.partial object at 0x2800ec0>
Traceback (most recent call last):
  File "/usr/lib64/python2.7/site-packages/tornado/ioloop.py", line 591, in _run_callback
    ret = callback()
  File "/usr/lib64/python2.7/site-packages/tornado/stack_context.py", line 342, in wrapped
    raise_exc_info(exc)
  File "/usr/lib64/python2.7/site-packages/tornado/stack_context.py", line 313, in wrapped
    ret = fn(*args, **kwargs)
  File "/usr/lib64/python2.7/site-packages/tornado/ioloop.py", line 597, in <lambda>
    self.add_future(ret, lambda f: f.result())
  File "/usr/lib64/python2.7/site-packages/tornado/concurrent.py", line 214, in result
    raise_exc_info(self._exc_info)
  File "/usr/lib64/python2.7/site-packages/tornado/gen.py", line 230, in wrapper
    yielded = next(result)
  File "/usr/lib/python2.7/site-packages/salt/crypt.py", line 595, in _authenticate
    io_loop=self.io_loop)
  File "/usr/lib/python2.7/site-packages/salt/transport/client.py", line 108, in factory
    return salt.transport.zeromq.AsyncZeroMQReqChannel(opts, **kwargs)
  File "/usr/lib/python2.7/site-packages/salt/transport/zeromq.py", line 133, in __new__
    obj.__singleton_init__(opts, **kwargs)
  File "/usr/lib/python2.7/site-packages/salt/transport/zeromq.py", line 197, in __singleton_init__
    kwargs={'io_loop': self._io_loop})
  File "/usr/lib/python2.7/site-packages/salt/transport/zeromq.py", line 927, in __init__
    super(AsyncReqMessageClientPool, self).__init__(AsyncReqMessageClient, opts, args=args, kwargs=kwargs)
  File "/usr/lib/python2.7/site-packages/salt/transport/__init__.py", line 71, in __init__
    self.message_clients = [tgt(*args, **kwargs) for _ in range(sock_pool_size)]
  File "/usr/lib/python2.7/site-packages/salt/transport/zeromq.py", line 974, in __init__
    self._init_socket()
  File "/usr/lib/python2.7/site-packages/salt/transport/zeromq.py", line 1028, in _init_socket
    self.stream = zmq.eventloop.zmqstream.ZMQStream(self.socket, io_loop=self.io_loop)
  File "/usr/lib64/python2.7/site-packages/zmq/eventloop/zmqstream.py", line 114, in __init__
    self._init_io_state()
  File "/usr/lib64/python2.7/site-packages/zmq/eventloop/zmqstream.py", line 535, in _init_io_state
    self.io_loop.add_handler(self.socket, self._handle_events, self._state)
  File "/usr/lib64/python2.7/site-packages/tornado/ioloop.py", line 703, in add_handler
    self._impl.register(fd, events | self.ERROR)
TypeError: argument must be an int, or have a fileno() method.

If I manually update the pyzmq using pip to 17.0.0 version, this exception disappears.

Observation - By default repo.saltstack.com is supplying python-zmq version 15.3, should this be updated?

Versions Report

Salt Version:
           Salt: 2018.3.0-n/a-a064a3e

Dependency Versions:
           cffi: Not Installed
       cherrypy: Not Installed
       dateutil: Not Installed
      docker-py: Not Installed
          gitdb: Not Installed
      gitpython: Not Installed
          ioflo: Not Installed
         Jinja2: 2.7.2
        libgit2: Not Installed
        libnacl: Not Installed
       M2Crypto: Not Installed
           Mako: Not Installed
   msgpack-pure: Not Installed
 msgpack-python: 0.5.1
   mysql-python: Not Installed
      pycparser: Not Installed
       pycrypto: 2.6.1
   pycryptodome: Not Installed
         pygit2: Not Installed
         Python: 2.7.5 (default, Aug  4 2017, 00:39:18)
   python-gnupg: Not Installed
         PyYAML: 3.11
          PyZMQ: 15.3.0
           RAET: Not Installed
          smmap: Not Installed
        timelib: Not Installed
        Tornado: 4.2.1
            ZMQ: 4.1.4

System Versions:
           dist: centos 7.4.1708 Core
         locale: UTF-8
        machine: x86_64
        release: 3.10.0-693.17.1.el7.x86_64
         system: Linux
        version: CentOS Linux 7.4.1708 Core