Test case

 
A Pipeline script job as follows, The aim of this pipeline is to show the feature of inheritFrom :
 

podTemplate(cloud: 'openshift', inheritFrom: 'nodejs', name: 'nodejs-p', label: 'nodejs-p', volumes: [
    persistentVolumeClaim(mountPath: '/home/jenkins/.npm', claimName: 'nodejs', readOnly: false)
]) {
 
  node("nodejs-p") {
    stage('BuildFrontend') {
      // some commands
    }
  }
}

podTemplate(cloud: 'openshift', inheritFrom: 'maven', name: 'maven-p', label: 'maven-p', volumes: [
    persistentVolumeClaim(mountPath: '/home/jenkins/.m2', claimName: 'maven', readOnly: false)
]) {
 
  node("maven-p") {
    stage('BuildBackend') {
       // some commands
    }
  }
}

Outcome

 
The first podTemplate definition works as expected.
 
The second podTemplate starts, but instead of using the inheritFrom defined ('maven') it is using the 'nodejs-p' as parent. 
 
As you guess is wrong and because the nodejs-p template is temporary, the plugin starts the default jenkins-slave container.
 
If you invert the podTemplate definitions inside the pipeline, so first maven-p and second nodejs-p you obtain the same behaviour. The first works as expected and the second fails.
 
It looks like a race condition issue.

Plugin-Version: 0.10
Hudson-Version: 2.7.4
Jenkins-Version: 2.7.4

Plugin-Version: 1.0
Hudson-Version: 2.32.1
Jenkins-Version: 2.32.1