VCRConnection does not support Python 3.6 - 'encode_chunked'

[derekbekoe]

In Python 3.6 http.client.HTTPConnection.request, a new keyword argument of encode_chunked was added. Currently, it doesn't look like VCR does not support this change so you get a stacktrace.
https://docs.python.org/3.6/library/http.client.html#http.client.HTTPConnection.request

When VCR patches HTTPConnection with vcr.patch.VCRHTTPSConnection, it does not accept this new keyword argument and so you see the following stacktrace for example:

  File "/usr/local/lib/python3.6/urllib/request.py", line 223, in urlopen
    return opener.open(url, data, timeout)
  File "/usr/local/lib/python3.6/urllib/request.py", line 526, in open
    response = self._open(req, data)
  File "/usr/local/lib/python3.6/urllib/request.py", line 544, in _open
    '_open', req)
  File "/usr/local/lib/python3.6/urllib/request.py", line 504, in _call_chain
    result = func(*args)
  File "/usr/local/lib/python3.6/urllib/request.py", line 1361, in https_open
    context=self._context, check_hostname=self._check_hostname)
  File "/usr/local/lib/python3.6/urllib/request.py", line 1318, in do_open
    encode_chunked=req.has_header('Transfer-encoding'))
TypeError: request() got an unexpected keyword argument 'encode_chunked'

Similar to: boto/botocore#1079 where the solution was in PR boto/botocore#1107 (accept the kwargs but don't use them).

---

More info:

In the do_open method of /usr/local/lib/python3.6/urllib/request.py, a http_class class is expected. VCR passes in the class vcr.patch.VCRHTTPSConnection (an instance of VCRConnection) for this.

In do_open, Python calls http_class(...).request(..., encode_chunked). Since VCR uses VCRHTTPSConnection here, VCRHTTPSConnection.request(). This method (https://github.com/kevin1024/vcrpy/blob/master/vcr/stubs/__init__.py#L156) does not accept the encode_chunked keyword and so we get TypeError: request() got an unexpected keyword argument 'encode_chunked'.