Peter,
FYI it's a known problem (JDK-8079205 [1]). The CallSite context logic is broken after sun.misc.Cleaner was made automatically clearable.- in java.lang.invoke.CallSite, to invalidate the dependent nmethods when the context class is GC-ed - that one was added recently. Intermittent failures of the test predate it's addition, so I would not suspect this one immediately.
Best regards, Vladimir Ivanov [1] https://bugs.openjdk.java.net/browse/JDK-8079205