This seems regression of fix for 7160252 and now for JDK-7184287 in jdk 9.

These 4 tests,
java/util/prefs/AddNodeChangeListener.java
java/util/prefs/CheckUserPrefsStorage.sh
java/util/prefs/RemoveReadOnlyNode.java
java/util/prefs/RemoveUnregedListener.java

Are failing with this stack trace
java.util.prefs.BackingStoreException: Synchronization failed for node '/'
at java.util.prefs.MacOSXPreferences.flush(MacOSXPreferences.java:226)
at AddNodeChangeListener.addNode(AddNodeChangeListener.java:60)
at AddNodeChangeListener.main(AddNodeChangeListener.java:46)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:502)
at com.sun.javatest.regtest.agent.MainWrapper$MainThread.run(MainWrapper.java:92)
at java.lang.Thread.run(Thread.java:745)

when run on mac as a non-root user.
It can be reproduced with the test case listed by AmyLu in JDK-7184287.
As non-root, compile and run and it fails with the above BackingStoreException.
sudo to root, run, and it passes.