Description:
grequests can't be imported on python3.7

Additional info:
* package version(s)

python 3.7.0-3
python-grequests 0.3.0-3

* config and/or log files etc.

/usr/lib/python3.7/importlib/_bootstrap.py:219: RuntimeWarning: greenlet.greenlet size changed, may indicate binary incompatibility. Expected 144, got 128
return f(*args, **kwds)
/usr/lib/python3.7/importlib/_bootstrap.py:219: RuntimeWarning: greenlet.greenlet size changed, may indicate binary incompatibility. Expected 144, got 128
return f(*args, **kwds)
/usr/lib/python3.7/importlib/_bootstrap.py:219: RuntimeWarning: greenlet.greenlet size changed, may indicate binary incompatibility. Expected 144, got 128
return f(*args, **kwds)
/usr/lib/python3.7/importlib/_bootstrap.py:219: RuntimeWarning: greenlet.greenlet size changed, may indicate binary incompatibility. Expected 144, got 128
return f(*args, **kwds)
/usr/lib/python3.7/importlib/_bootstrap.py:219: RuntimeWarning: greenlet.greenlet size changed, may indicate binary incompatibility. Expected 144, got 128
return f(*args, **kwds)
/usr/lib/python3.7/importlib/_bootstrap.py:219: RuntimeWarning: greenlet.greenlet size changed, may indicate binary incompatibility. Expected 144, got 128
return f(*args, **kwds)
/usr/lib/python3.7/importlib/_bootstrap.py:219: RuntimeWarning: greenlet.greenlet size changed, may indicate binary incompatibility. Expected 144, got 128
return f(*args, **kwds)
Traceback (most recent call last):
File "<string>", line 1, in <module>
File "/usr/lib/python3.7/site-packages/grequests.py", line 23, in <module>
from requests import Session
File "/usr/lib/python3.7/site-packages/requests/__init__.py", line 95, in <module>
from urllib3.contrib import pyopenssl
File "/usr/lib/python3.7/site-packages/urllib3/contrib/pyopenssl.py", line 46, in <module>
import OpenSSL.SSL
File "/usr/lib/python3.7/site-packages/OpenSSL/__init__.py", line 8, in <module>
from OpenSSL import crypto, SSL
File "/usr/lib/python3.7/site-packages/OpenSSL/crypto.py", line 12, in <module>
from cryptography import x509
File "/usr/lib/python3.7/site-packages/cryptography/x509/__init__.py", line 8, in <module>
from cryptography.x509.base import (
File "/usr/lib/python3.7/site-packages/cryptography/x509/base.py", line 16, in <module>
from cryptography.x509.extensions import Extension, ExtensionType
File "/usr/lib/python3.7/site-packages/cryptography/x509/extensions.py", line 13, in <module>
from asn1crypto.keys import PublicKeyInfo
File "/usr/lib/python3.7/site-packages/asn1crypto/keys.py", line 22, in <module>
from ._elliptic_curve import (
File "/usr/lib/python3.7/site-packages/asn1crypto/_elliptic_curve.py", line 51, in <module>
from ._int import inverse_mod
File "/usr/lib/python3.7/site-packages/asn1crypto/_int.py", line 56, in <module>
from ._perf._big_num_ctypes import libcrypto
File "/usr/lib/python3.7/site-packages/asn1crypto/_perf/_big_num_ctypes.py", line 35, in <module>
libcrypto_path = find_library(b'crypto' if sys.version_info < (3,) else 'crypto')
File "/usr/lib/python3.7/ctypes/util.py", line 311, in find_library
return _findSoname_ldconfig(name) or \
File "/usr/lib/python3.7/ctypes/util.py", line 280, in _findSoname_ldconfig
env={'LC_ALL': 'C', 'LANG': 'C'}) as p:
File "/usr/lib/python3.7/site-packages/gevent/subprocess.py", line 463, in __init__
hub = get_hub()
File "src/gevent/_hub_local.py", line 73, in gevent.__hub_local.get_hub_noargs
File "src/gevent/_hub_local.py", line 80, in gevent.__hub_local.get_hub_noargs
File "/usr/lib/python3.7/site-packages/gevent/hub.py", line 390, in __init__
WaitOperationsGreenlet.__init__(self, None, None)
File "src/gevent/_greenlet_primitives.py", line 42, in gevent.__greenlet_primitives.TrackedRawGreenlet.__init__
SystemError: Objects/dictobject.c:1439: bad argument to internal function


Steps to reproduce:
python3.7 -c 'import grequests'