Nameko can not work with pathlib

[YAGregor]

Describe the bug
nameko worker process raise an exception when calling Path('anything').open(). reference to this issue, that should caused by a bug of eventlet.

To Reproduce
server.py

from pathlib import Path
from nameko.rpc import rpc


class Test:
    name = 'test'

    @rpc
    def test(self):
        Path('anything').open()

client.py

from nameko.standalone.rpc import ClusterRpcProxy

with ClusterRpcProxy({'AMQP_URI': 'pyamqp://guest:guest@localhost'}) as cluster_rpc:
    cluster_rpc.test.test()

run command line nameko run server and python client.py.
Expected behavior
client crushed and server raised a exception. exception on my machine:

Traceback (most recent call last):
  File "/home/***/.local/share/virtualenvs/judger-uPeNMyNf/lib/python3.7/site-packages/nameko/containers.py", line 392, in _run_worker
    result = method(*worker_ctx.args, **worker_ctx.kwargs)
  File "./server.py", line 10, in test
    Path('anything').open()
  File "/usr/lib64/python3.7/pathlib.py", line 1186, in open
    opener=self._opener)
  File "/usr/lib64/python3.7/pathlib.py", line 1039, in _opener
    return self._accessor.open(self, flags, mode)
  File "/home/***/.local/share/virtualenvs/judger-uPeNMyNf/lib/python3.7/site-packages/eventlet/green/os.py", line 107, in open
    fd = __original_open__(file, flags, mode, dir_fd=dir_fd)
TypeError: open: path should be string, bytes or os.PathLike, not _NormalAccessor

Environment (please complete the following information):

• Nameko version: 2.12.0
• Python version: 3.7.3
• OS: Manjaro/Linux

[daviskirk]

As a simple workaround, in python >= 3.6 you should be able to use the normal builtin open function on pathlib objects. This seems to work fine and should have the exact same result (but without the crash):

import pathlib 

class Test:
    name = 'test'

    @rpc
    def test(self):
        open(Path('anything'))

[davidszotten]

eventlet 0.25.1 is now available with a fix for the pathlib issue