Merged revision(s) 1559346 from ofbiz/branches/release12.04:

Small rewrite in JobManager.java to fix a bug where jobs could be duplicated under certain conditions. https://issues.apache.org/jira/browse/OFBIZ-5496


git-svn-id: https://svn.apache.org/repos/asf/ofbiz/branches/release11.04@1559353 13f79535-47bb-0310-9956-ffa450edef68