Cancel a request using buildapi self-serve. Returns a request.

    Buildapi documentation:
    DELETE /self-serve/{branch}/request/{request_id} Cancel the given request

def make_cancel_request(repo_name, request_id, auth, dry_run=True):
    """
    Cancel a request using buildapi self-serve. Returns a request.

    Buildapi documentation:
    DELETE /self-serve/{branch}/request/{request_id} Cancel the given request
    """
    url = '{}/{}/request/{}'.format(SELF_SERVE, repo_name, request_id)

    if dry_run:
        LOG.info('We would make a DELETE request to %s.' % url)
        return None

    LOG.info("We're going to cancel the job at %s" % url)
    req = requests.delete(url, auth=auth, timeout=TCP_TIMEOUT)
    # TODO: add debug message with the canceled job_id URL. Find a way
    # to do that without doing an additional request.
    return req