In the latest version of Jenkins, the default value of 'disabled' is
true. When 'disabled' is not set (or None), reconfig_job will activate
the job, but in some cases we hope that 'disabled' remain the last
setting.
When 'disabled' is not set (or None) in yaml, and the job exists,
fix_disabled will try to get 'disabled' from the jenkins server. So the
'disabled' value should match the current value on the jenkins server.
Change-Id: Icd840f15c4d48cd8a8ebc0f891beac68c2bb6bdd
7712c0b7ee