When using Maven 3.2.1 with Jenkins 1.555 the unit tests block with a LinkageError like this:

Running asf.artifact.ArtifactHandlerManagerTest
Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.149 sec - in asf.artifact.ArtifactHandlerManagerTest
Exception in thread "Thread-11" java.lang.LinkageError: org.apache.maven.surefire.shade.org.apache.maven.shared.utils.io.IOUtil
at java.lang.ClassLoader.defineClassImpl(Native Method)
at java.lang.ClassLoader.defineClass(ClassLoader.java:364)
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:154)
at java.net.URLClassLoader.defineClass(URLClassLoader.java:777)
at java.net.URLClassLoader.access$400(URLClassLoader.java:96)
at java.net.URLClassLoader$ClassFinder.run(URLClassLoader.java:1225)
at java.security.AccessController.doPrivileged(AccessController.java:366)
at java.net.URLClassLoader.findClass(URLClassLoader.java:660)
at org.codehaus.plexus.classworlds.realm.ClassRealm.loadClassFromSelf(ClassRealm.java:389)
at org.codehaus.plexus.classworlds.strategy.SelfFirstStrategy.loadClass(SelfFirstStrategy.java:42)
at org.codehaus.plexus.classworlds.realm.ClassRealm.unsynchronizedLoadClass(ClassRealm.java:259)
at org.codehaus.plexus.classworlds.realm.ClassRealm.loadClass(ClassRealm.java:235)
at org.codehaus.plexus.classworlds.realm.ClassRealm.loadClass(ClassRealm.java:227)
at org.apache.maven.surefire.shade.org.apache.maven.shared.utils.cli.StreamPumper.run(StreamPumper.java:95)

Once this error occurs the Jenkins job blocks.

I do not get these errors if I run the unit tests directly with Maven 3.2.1

I could not find anything of interest in the Manage Jenkins -> Jenkins log

I am also seeing this error occasionally with Maven 3.1.1