I just created a new job that only contains a Parallel Test Execution.
Tried the job with both a matrix job, and a regular maven job.
Both fail with this exception:

Copying file to
FATAL: Failed to copy /var/lib/jenkins/jobs/backstage.ParallelTestExecution/builds/2013-06-06_20-20-25/parameter-files/test-splits/split.1.txt to /home/builder/workspace/backstage.Test.chrome
hudson.util.IOException2: Failed to copy /var/lib/jenkins/jobs/backstage.ParallelTestExecution/builds/2013-06-06_20-20-25/parameter-files/test-splits/split.1.txt to /home/builder/workspace/backstage.Test.chrome
at hudson.FilePath.copyTo(FilePath.java:1726)
at hudson.model.FileParameterValue$FileItemImpl.write(FileParameterValue.java:267)
at hudson.FilePath.copyFrom(FilePath.java:830)
at hudson.model.FileParameterValue$2.setUp(FileParameterValue.java:136)
at hudson.model.Build$BuildExecution.doRun(Build.java:154)
at hudson.model.AbstractBuild$AbstractBuildExecution.run(AbstractBuild.java:586)
at hudson.model.Run.execute(Run.java:1576)
at hudson.model.FreeStyleBuild.run(FreeStyleBuild.java:46)
at hudson.model.ResourceController.execute(ResourceController.java:88)
at hudson.model.Executor.run(Executor.java:241)
Caused by: java.io.FileNotFoundException: /home/builder/workspace/backstage.Test.chrome (Is a directory)
at java.io.FileOutputStream.open(Native Method)
at java.io.FileOutputStream.<init>(FileOutputStream.java:179)
at java.io.FileOutputStream.<init>(FileOutputStream.java:131)
at hudson.FilePath.write(FilePath.java:1622)
at hudson.FilePath.copyTo(FilePath.java:1719)
... 9 more