Request Review JDK-8180574: tools/launcher/modules/patch/systemmodules/PatchSystemModules.java failed in upgradeHashedModule() and patchHashedModule() intermittently

[Mandy Chung]

http://cr.openjdk.java.net/~mchung/jdk9/webrevs/8180574/webrev.00/

The test fails intermittently that the hash of new_m1.jar might be the 
same value as m1.jar that is hashed in m2.  Unfortunately I haven’t 
managed to reproduce the test failure with my instrumented test to
confirm.  I propose to change the test to upgrade a different version
of m1 rather than the same content and observe if this test would
fail again.

Mandy