hg: shenandoah/jdk: Fix bad assertion: can see non-empty task queue during canceled GC cycle

[zgu at redhat.com]

Changeset: d635c99f02e8
Author:    zgu
Date:      2018-08-13 13:18 -0400
URL:       http://hg.openjdk.java.net/shenandoah/jdk/rev/d635c99f02e8

Fix bad assertion: can see non-empty task queue during canceled GC cycle

! src/hotspot/share/gc/shenandoah/shenandoahTraversalGC.cpp