I have master/slave setup, and my project has the ability to execute builds in parallel, i.e. I have 'Execute concurrent builds if necessary' option turned on.

But when I'm trying to inject any environment variables into my job ( 'Inject environment variables to the build process' option ), then the $WORKSPACE variable is NOT defined properly for parallel builds.

They should be

${JENKINS_HOME/workspace/${JOB_NAME}
${JENKINS_HOME/workspace/${JOB_NAME}@2
${JENKINS_HOME/workspace/${JOB_NAME}@3
...
But $WORKSPACE always points to

${JENKINS_HOME/workspace/${JOB_NAME}
for all job runs.