[oozie] Incorrect timezone in job.properties

With HUE-1910, oozie.processing.timezone is used in the Web UI. However, the generated start_date and end_date in job.properties is still UTC.

The following code seems responsible for that:

def convert_to_server_timezone(date, local_tz='UTC', server_tz='UTC', user=DEFAULT_USER):
  api = get_oozie(user)
  oozie_conf = api.get_configuration()
  if server_tz is None:
    server_tz = oozie_conf['oozie.processing.timezone']

server_tz should have the default value of None instead of 'UTC'?