title: Ear is not built on Jenkins with maven-ear-plugin
body: <p>While executing mvn install on jenkins I get this error:</p>
  
  <blockquote>
    <p>[JENKINS] Archiving disabled
        Waiting for Jenkins to finish collecting data
        mavenExecutionResult exceptions not empty
        message : Failed to execute goal org.apache.maven.plugins:maven-ear-plugin:2.9:ear (default-ear) on
    project proj-ear: Cannot copy a directory:
    /var/lib/jenkins/jobs/proj/workspace/proj-lib/target/classes; Did you
    package/install com.xxx.proj-lib:jar:1.0.6-SNAPSHOT:compile?</p>
  </blockquote>
  
  <p>Locally everything builds OK. Do you have any idea how to solve this?</p>