It is an intermittent failure. I reproduced once on Oracle Linux 5.6 32 bit with 5 times reruns. But tried tens of times. no one reproduced on another Oracle Linux 6.4 environment.

Test output:
----------messages:(3/107)----------
command: main Test6a
reason: User specified action: run main/othervm Test6a
elapsed time (seconds): 1.365
----------System.out:(1/9)----------
Test6a:
----------System.err:(17/1096)----------
java.io.IOException: Error writing request body to server
at sun.net.www.protocol.http.HttpURLConnection$StreamingOutputStream.checkError(HttpURLConnection.java:3487)
at sun.net.www.protocol.http.HttpURLConnection$StreamingOutputStream.write(HttpURLConnection.java:3470)
at java.io.BufferedOutputStream.flushBuffer(BufferedOutputStream.java:81)
at java.io.BufferedOutputStream.write(BufferedOutputStream.java:95)
at Test6a.main(Test6a.java:68)
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)