Works perfectly with xUnit 1.14, but after upgrading to 1.15:

[xUnit] [INFO] - Starting to record.
[xUnit] [INFO] - Processing PHPUnit-3.4 (default)
[xUnit] [INFO] - [PHPUnit-3.4 (default)] - 1 test report file(s) were found with the pattern 'build/logs/junit.xml' relative to '/var/lib/jenkins/jobs/MyDemo/workspace' for the testing framework 'PHPUnit-3.4 (default)'.
[xUnit] [ERROR] - The plugin hasn't been performed correctly: null
Recording plot data
Publishing Clover coverage report...
Publishing Clover XML report...
Publishing Clover coverage results...
Finished: FAILURE