After the initial fix for JDK-8218446 we encountered a crash, so it was backed out.

Running test: jdk/com/sun/jdi/MultiBreakpointsTest.java

#
# A fatal error has been detected by the Java Runtime Environment:
#
# Internal Error (/scratch/opt/mach5/mesos/work_dir/slaves/07fc96ef-bf4d-487f-b22f-a84e49f5f44a-S7323/frameworks/1735e8a2-a1db-478c-8104-60c8b0af87dd-0196/executors/abb66f1d-68b6-4482-978f-5b998112562d/runs/bbb5d27a-fd14-4acc-83a8-a251596e5872/workspace/open/src/hotspot/share/runtime/safepoint.cpp:827), pid=16263, tid=16321
# fatal error: Illegal threadstate encountered: 4
#
# JRE version: Java(TM) SE Runtime Environment (13.0) (fastdebug build 13-internal+0-jdk13-jdk.656)
# Java VM: Java HotSpot(TM) 64-Bit Server VM (fastdebug 13-internal+0-jdk13-jdk.656, mixed mode, sharing, tiered, compressed oops, serial gc, linux-amd64)
# Problematic frame:
# V [libjvm.so+0x14b1fee] SafepointSynchronize::block(JavaThread*)+0xae
#
...
--------------- T H R E A D ---------------

Current thread (0x00007fc3c0258000): JavaThread "2" [_thread_in_native, id=16321, stack(0x00007fc3c56e0000,0x00007fc3c57e1000)]

Stack: [0x00007fc3c56e0000,0x00007fc3c57e1000], sp=0x00007fc3c57ddba0, free space=1014k
Native frames: (J=compiled Java code, A=aot compiled Java code, j=interpreted, Vv=VM code, C=native code)
V [libjvm.so+0x14b1fee] SafepointSynchronize::block(JavaThread*)+0xae
V [libjvm.so+0x14ba78d] SafepointMechanism::block_if_requested_slow(JavaThread*)+0x6d
V [libjvm.so+0x1637207] JavaThread::handle_special_runtime_exit_condition(bool)+0x67
V [libjvm.so+0x1073b1e] JvmtiJavaThreadEventTransition::JvmtiJavaThreadEventTransition(JavaThread*)+0x1ae
V [libjvm.so+0x1069990] JvmtiExport::post_class_prepare(JavaThread*, Klass*)+0x1b0
V [libjvm.so+0xd87021] InstanceKlass::link_class_impl(Thread*)+0x421
V [libjvm.so+0xd87471] InstanceKlass::link_class(Thread*)+0x71

It is not valid to call SafepointSynchronize::block from the thread-state _thread_in_native (threads in native are by definition safepoint safe).