There are several places in the source code where
HTTP response codes are used as numeric values.
These values are used from six.moves and the
numeric values are replaced by constants.
All of the used status codes were replaced with symbolic constants
from six.moves.http_client.
More about six.moves.http_client can be found at [2],
under the table "Supported renames:".
Also, this change improves code readibility.
This patchset does not extract numeric values from
the code itself, but it can be found at [1].
[1]: Ib9e26dcea927e96e65c626c18421621d3a29a64d
[2]: https://pythonhosted.org/six/#module-six.moves
Change-Id: Idfc7b043552f428f01ac3e47b270ee0639a8f5bc
Closes-Bug: #1520159
8a8e5bf56c