If mapred.job.name is set in the configuration parameters of a Hive Action, one sees that the setting doesn't stick. The Hive job runs with the default hive job-name (i.e. the query, truncated to a certain length). This behaviour prevents users from being able to choose custom job-names for Hive-jobs launched from Oozie workflows.
The Hive configuration indicates that mapred.job.name (and mapreduce.job.name) are passed into Hive as empty ("").