Alan, Michael,This is an old issue. JAR URLs may not compare equal when their enclosing URL's are. The reason is that URLStreamHandle.equals(URL,URL) and sameFile(URL,URL) doesn't know about the composite URL syntax used by JAR URLs. To resolve this we should overridden samefile in sun.net.www.protocol.jar.Handler. Ditto for hashCode.
http://cr.openjdk.java.net/~chegar/7030649/webrev.00/webrev/ -Chris.
