IllegalArgumentException at job start on storage dirs creation

[hlerebours]

Issue type: Bug report

My Rundeck detail

• Rundeck version: seen on 2.6.4, but the bug should still exist according to the code on master
• install type: launcher
• OS Name/version: CentOs / 2.6.32-642.1.1.el6.centos.plus.x86_64 and 4.4.21-1.el7.elrepo.x86_64

Expected Behavior
A job looking at the key storage should be able to be launched multiple times in parallel after a Rundeck fresh start

Actual Behavior
Job output:
Failed to start execution: java.lang.IllegalArgumentException: Unable to create root dir: [...]/var/storage

How to reproduce Behavior
Start a new Rundeck instance without any key storage configured, create a job taking an optional parameter defaulting in a key storage entry, start it multiple times in parallel.