Issue

Building a pipeline job with parallel steps, whenever I cancel a parallel step that waits in the Build Queue, the corresponding job hangs.

Reproduce

• I have a node label osx-master that contains 2 nodes
• Each node has one executor
• I create a pipeline script like the following

    def branches = [:] 
    branches["one"] = { 
        node('osx-master'){ 
            echo "branch 1: here is something that happens in stage one" 
            sh "sleep 10" 
        } 
    } 
    branches["two"] = { 
        node('osx-master'){ 
            echo "branch 2: here is something that happens in stage one" 
            sh "sleep 10" 
        } 
    } 
    parallel branches 
    echo "Done with build" 

• I run 2 builds concurrently - for example #15 and #16
• #15 tasks are immediately picked up from the build queue and are executed
• #16 tasks shows up in the Build Queue
• I cancel one of #16 tasks from the Build Queue. It disappears
• #15 end with SUCCESS
• #16 never ends and hangs...

Attached logs of:

• Queue-Executors.log: `hudson.model.Queue` and `hudson.model.Executors`
• Pipeline.log: `org.jenkinsci.plugins.workflow.flow`, `org.jenkinsci.plugins.workflow.job` and `org.jenkinsci.plugins.workflow.support`