datastore v1beta3 doesn't handle errors properly

[pcostell]

In Datastore v1beta3, the error response is a serialized proto message Status. However, the error handling currently tries to decode it, which can fail with a unicode error.

  File "./main.py", line 20, in lookup
    print(client.get(key))
  File "/Users/pcostello/.local/virtualenvs/gcloud-permissions-v1beta3/src/gcloud/gcloud/datastore/client.py", line 248, in get
    deferred=deferred)
  File "/Users/pcostello/.local/virtualenvs/gcloud-permissions-v1beta3/src/gcloud/gcloud/datastore/client.py", line 289, in get_multi
    transaction_id=transaction and transaction.id,
  File "/Users/pcostello/.local/virtualenvs/gcloud-permissions-v1beta3/src/gcloud/gcloud/datastore/client.py", line 122, in _extended_lookup
    transaction_id=transaction_id,
  File "/Users/pcostello/.local/virtualenvs/gcloud-permissions-v1beta3/src/gcloud/gcloud/datastore/connection.py", line 197, in lookup
    _datastore_pb2.LookupResponse)
  File "/Users/pcostello/.local/virtualenvs/gcloud-permissions-v1beta3/src/gcloud/gcloud/datastore/connection.py", line 115, in _rpc
    data=request_pb.SerializeToString())
  File "/Users/pcostello/.local/virtualenvs/gcloud-permissions-v1beta3/src/gcloud/gcloud/datastore/connection.py", line 92, in _request
    raise make_exception(headers, content, use_json=False)
  File "/Users/pcostello/.local/virtualenvs/gcloud-permissions-v1beta3/src/gcloud/gcloud/exceptions.py", line 181, in make_exception
    content = content.decode('utf-8')
  File "/Users/pcostello/.local/virtualenvs/gcloud-permissions-v1beta3/lib/python2.7/encodings/utf_8.py", line 16, in decode
    return codecs.utf_8_decode(input, errors, True)
UnicodeDecodeError: 'utf8' codec can't decode byte 0xa8 in position 20: invalid start byte

[pcostell]

I attached #1618 which shows what the expected response is. I can updated it and submit it if you want, but it's just a hack to show the issue.

[dhermes]

Thanks @pcostell. We discussed this in #1466 and I added it as a TODO in #1288 but hadn't gotten to it yet.

Some good news is that googleapis-common-protos actually includes status_pb2 so we don't have to do anything extra to get it.

[pcostell]

Ah I totally forgot. It seems potentially more important than I realized since now users will fail with utf-8 decoding issues with no indication of the actual error.

[dhermes]

Yes. When reporting an error causes an error, that's a problem

[pcostell]

Fixed by #1638