This happened once in 9 b179 promotion testing. It is not observed in the history results and unable to reproduce with repeated runs on the same host.

Test output:
----------System.err:(20/1404)----------
java.net.SocketException: Unexpected end of file from server
at java.base/sun.net.www.http.HttpClient.parseHTTPHeader(HttpClient.java:862)
at java.base/sun.net.www.http.HttpClient.parseHTTP(HttpClient.java:689)
at java.base/sun.net.www.http.HttpClient.parseHTTPHeader(HttpClient.java:859)
at java.base/sun.net.www.http.HttpClient.parseHTTP(HttpClient.java:689)
at java.base/sun.net.www.protocol.http.HttpURLConnection.getInputStream0(HttpURLConnection.java:1586)
at java.base/sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1491)
at LocalHostCookie.runTest(LocalHostCookie.java:56)
at LocalHostCookie.main(LocalHostCookie.java:43)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:564)
at com.sun.javatest.regtest.agent.MainWrapper$MainThread.run(MainWrapper.java:115)
at java.base/java.lang.Thread.run(Thread.java:844)