Description of problem:
Failed to initiate a connection to the engine with the new v4 sdk if specified the version number in url:

import ovirtsdk4 as sdk
import ovirtsdk4.types as types
api = sdk.Connection(url="https://{engine_url}/ovirt-engine/api/v4", username='{user@domain}', password='{pass}', insecure=True)
vm_pool_service = api.system_service().vm_pools_service()
vm_pool_service.list()
Traceback (most recent call last):
  File "<input>", line 1, in <module>
    vm_pool_service.list()
  File "/usr/lib64/python2.7/site-packages/ovirtsdk4/services.py", line 20254, in list
    response = self._connection.send(request)
  File "/usr/lib64/python2.7/site-packages/ovirtsdk4/__init__.py", line 281, in send
    return self.__send(request)
  File "/usr/lib64/python2.7/site-packages/ovirtsdk4/__init__.py", line 292, in __send
    self._sso_token = self._get_access_token()
  File "/usr/lib64/python2.7/site-packages/ovirtsdk4/__init__.py", line 450, in _get_access_token
    sso_response = self._get_sso_response(self._sso_url)
  File "/usr/lib64/python2.7/site-packages/ovirtsdk4/__init__.py", line 488, in _get_sso_response
    return json.loads(body_buf.getvalue().decode('utf-8'))
  File "/usr/lib64/python2.7/json/__init__.py", line 338, in loads
    return _default_decoder.decode(s)
  File "/usr/lib64/python2.7/json/decoder.py", line 366, in decode
    obj, end = self.raw_decode(s, idx=_w(s, 0).end())
  File "/usr/lib64/python2.7/json/decoder.py", line 384, in raw_decode
    raise ValueError("No JSON object could be decoded")
ValueError: No JSON object could be decoded

Works fine when connecting with url without the v4 flag in the url.


Version-Release number of selected component (if applicable):
python-ovirt-engine-sdk4-4.0.0-0.5.a5.el7ev.x86_64

How reproducible:
seems to happen always.

Steps to Reproduce:
as mentioned above.

Actual results:
couldn't get the list of vm pools in this specific case (happens with all entities).

Expected results:
succeed to get list of all entities as normal.