[Graal] org.graalvm.compiler.core.test.CountedLoopTest fails with "ControlFlowAnchor should never be cloned in the same graph"

org.graalvm.compiler.core.test.CountedLoopTest ran with Graal as JIT fails with "ControlFlowAnchor should never be cloned in the same graph"
assertion when running using latest jdk/hs fastdebug bits. The full error log is

org.graalvm.compiler.core.test.CountedLoopTest started (1 of 1)
  incrementEq1: Passed
  incrementEq2: Passed
  incrementEq3: Passed
  incrementEq4: Passed
  incrementEq5: Passed
  incrementEq6: Passed
  incrementEq7: Dumping debug output in /home/katya/work/JavaSE/Hotspot/ws/jdk.hs/open/src/jdk.internal.vm.compiler/share/dumps/1521571093746
Thread[JVMCI CompilerThread0,9,system]: Compilation of org.graalvm.compiler.core.test.CountedLoopTest.incrementEqSnippet(int, int, int) failed: java.lang.AssertionError: 54|ControlFlowAnchor should never be cloned in the same graph
        at jdk.internal.vm.compiler@11-internal/org.graalvm.compiler.nodes.debug.ControlFlowAnchorNode.afterClone(ControlFlowAnchorNode.java:66)
        at jdk.internal.vm.compiler@11-internal/org.graalvm.compiler.graph.Node.clone(Node.java:933)
        at jdk.internal.vm.compiler@11-internal/org.graalvm.compiler.graph.NodeClass.createNodeDuplicates(NodeClass.java:899)
        at jdk.internal.vm.compiler@11-internal/org.graalvm.compiler.graph.NodeClass.addGraphDuplicate(NodeClass.java:848)
        at jdk.internal.vm.compiler@11-internal/org.graalvm.compiler.graph.Graph.addDuplicates(Graph.java:1252)
        at jdk.internal.vm.compiler@11-internal/org.graalvm.compiler.loop.LoopFragment.patchNodes(LoopFragment.java:178)
        at jdk.internal.vm.compiler@11-internal/org.graalvm.compiler.loop.LoopFragmentInside.insertBefore(LoopFragmentInside.java:135)
        at jdk.internal.vm.compiler@11-internal/org.graalvm.compiler.loop.phases.LoopTransformations.peel(LoopTransformations.java:78)
        at jdk.internal.vm.compiler@11-internal/org.graalvm.compiler.hotspot.phases.OnStackReplacementPhase.run(OnStackReplacementPhase.java:151)
        at jdk.internal.vm.compiler@11-internal/org.graalvm.compiler.phases.Phase.run(Phase.java:47)
        at jdk.internal.vm.compiler@11-internal/org.graalvm.compiler.phases.BasePhase.apply(BasePhase.java:195)
        at jdk.internal.vm.compiler@11-internal/org.graalvm.compiler.phases.BasePhase.apply(BasePhase.java:137)
        at jdk.internal.vm.compiler@11-internal/org.graalvm.compiler.phases.PhaseSuite.run(PhaseSuite.java:210)
        at jdk.internal.vm.compiler@11-internal/org.graalvm.compiler.phases.BasePhase.apply(BasePhase.java:195)
        at jdk.internal.vm.compiler@11-internal/org.graalvm.compiler.phases.BasePhase.apply(BasePhase.java:137)
        at jdk.internal.vm.compiler@11-internal/org.graalvm.compiler.core.GraalCompiler.emitFrontEnd(GraalCompiler.java:222)
        at jdk.internal.vm.compiler@11-internal/org.graalvm.compiler.core.GraalCompiler.compile(GraalCompiler.java:172)
        at jdk.internal.vm.compiler@11-internal/org.graalvm.compiler.core.GraalCompiler.compileGraph(GraalCompiler.java:158)
        at jdk.internal.vm.compiler@11-internal/org.graalvm.compiler.hotspot.HotSpotGraalCompiler.compileHelper(HotSpotGraalCompiler.java:189)
        at jdk.internal.vm.compiler@11-internal/org.graalvm.compiler.hotspot.HotSpotGraalCompiler.compile(HotSpotGraalCompiler.java:202)
        at jdk.internal.vm.compiler@11-internal/org.graalvm.compiler.hotspot.CompilationTask$HotSpotCompilationWrapper.performCompilation(CompilationTask.java:169)
        at jdk.internal.vm.compiler@11-internal/org.graalvm.compiler.hotspot.CompilationTask$HotSpotCompilationWrapper.performCompilation(CompilationTask.java:94)
        at jdk.internal.vm.compiler@11-internal/org.graalvm.compiler.core.CompilationWrapper.run(CompilationWrapper.java:165)
        at jdk.internal.vm.compiler@11-internal/org.graalvm.compiler.hotspot.CompilationTask.runCompilation(CompilationTask.java:317)
        at jdk.internal.vm.compiler@11-internal/org.graalvm.compiler.hotspot.HotSpotGraalCompiler.compileMethod(HotSpotGraalCompiler.java:142)
        at jdk.internal.vm.compiler@11-internal/org.graalvm.compiler.hotspot.HotSpotGraalCompiler.compileMethod(HotSpotGraalCompiler.java:108)
        at jdk.internal.vm.ci/jdk.vm.ci.hotspot.HotSpotJVMCIRuntime.compileMethod(HotSpotJVMCIRuntime.java:443)


The test doesn't fail in case Graal as JIT is not used (-XX:+TieredCompilation -XX:+UseJVMCICompiler -Djvmci.Compiler=graal).