No, MAPREDUCE-6441 is fixing a slightly different problem where multiple jobs are running from the same user. This is addressing a problem when two different users on the same node try to run local jobs, not necessarily at the same time. Even after the latest patch for MAPREDUCE-6441 is applied LocalJobRunner is still referencing JTConfig.JT_STAGING_AREA_ROOT, and that will break for multiple users after
MAPREDUCE-5762 removed the default value for that property in mapred-default.xml.
I went through the list of properties removed by
MAPREDUCE-5762, and I created a patch that adds back any property that is being used by the code where the value in mapred-default.xml didn't match the default values in the code. One exception was mapreduce.cluster.temp.dir, but I suspect users are still referencing that value either directly or in their code.