jtreg:
jtreg, version 4.2 fcs b12
Installed in /home/rehn/bin/jtreg/lib/jtreg.jar
Running on platform version 9.0.4 from /usr/lib/jvm/java-9-openjdk-9.0.4.11-4.fc27.x86_64.
Built with Java(TM) 2 SDK, Version 1.8.0-b132 on January 20, 2018.
Copyright (c) 1999, 2016, Oracle and/or its affiliates. All rights reserved.
Use is subject to license terms.
JTHarness: version 5.0
JCov 2.0-b18 beta
TestNG: version 6.9.5
AsmTools: version 7.0

>make exploded-run-test-hotspot_handshake
...
Running test 'jtreg:open/test/hotspot/jtreg:hotspot_handshake'
Error: cannot determine version for JDK: /home/rehn/source/jdk/small/build/linux-x86_64-normal-server-slowdebug/jdk
Finished running test 'jtreg:open/test/hotspot/jtreg:hotspot_handshake'
Test report is stored in /home/rehn/source/jdk/small/build/linux-x86_64-normal-server-slowdebug/test-results/jtreg_open_test_hotspot_jtreg_hotspot_handshake

Maybe not jtreg bug, but something changed in makefiles.