Corrupt XML configuration in unit tests

I am seeing occasional smoke test failures, due to corrupt xml configuration in standalone.xml.

The test where I am seeing this failure is org.jboss.as.test.surefire.servermodule.HttpDeploymentUploadUnitTestCase, which occasionally ends up with additional junk at the end of it's standalone.xml file such as:

</system-properties>
</server>et-binding-group>
<system-properties>
<property name="foo" value="bar"/>
<property name="key" value="value"/>
</system-properties>
</server>

I am 99% sure this is caused by multiple concurrent calls to XmlConfigurationPersister.store, as when I synchronised this method on XmlConfigurationPersister I could no longer reproduce the problem (could have been just luck, but it seems highly unlikely).