Before this fix, it was noticed that the rclone webdav client did not
re-use HTTP connections when it should have been.
This turned out to be because rclone was not draining the HTTP bodies
when it was not expecting a response.
From the Go docs:
> If the returned error is nil, the Response will contain a non-nil
> Body which the user is expected to close. If the Body is not both
> read to EOF and closed, the Client's underlying RoundTripper
> (typically Transport) may not be able to re-use a persistent TCP
> connection to the server for a subsequent "keep-alive" request.
This fixes the problem by draining up to 10MB of data from an HTTP
response if the NoResponse flag is set, or at the end of a JSON or XML
response (which could have some whitespace on the end).
See: https://forum.rclone.org/t/webdav-with-persistent-connections/37024/
2e2451f8ec