Error during multi-threaded compaction in 0.8

I'm running 0.8.6 plus the multi-threaded compaction patch in issue 2901. I'm getting an error compacting last night:

Error occured during compaction
java.util.concurrent.ExecutionException: java.lang.ClassCastException: java.util.concurrent.ThreadPoolExecutor cannot be cast to org.apache.cassandra.concurrent.DebuggableThreadPoolExecutor
at java.util.concurrent.FutureTask$Sync.innerGet(FutureTask.java:222)
at java.util.concurrent.FutureTask.get(FutureTask.java:83)
at org.apache.cassandra.db.compaction.CompactionManager.performMajor(CompactionManager.java:278)
at org.apache.cassandra.db.ColumnFamilyStore.forceMajorCompaction(ColumnFamilyStore.java:1856)
at org.apache.cassandra.service.StorageService.forceTableCompaction(StorageService.java:1447)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at com.sun.jmx.mbeanserver.StandardMBeanIntrospector.invokeM2(StandardMBeanIntrospector.java:93)
at com.sun.jmx.mbeanserver.StandardMBeanIntrospector.invokeM2(StandardMBeanIntrospector.java:27)
at com.sun.jmx.mbeanserver.MBeanIntrospector.invokeM(MBeanIntrospector.java:208)
at com.sun.jmx.mbeanserver.PerInterface.invoke(PerInterface.java:120)
at com.sun.jmx.mbeanserver.MBeanSupport.invoke(MBeanSupport.java:262)
at com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.invoke(DefaultMBeanServerInterceptor.java:836)
at com.sun.jmx.mbeanserver.JmxMBeanServer.invoke(JmxMBeanServer.java:761)
at javax.management.remote.rmi.RMIConnectionImpl.doOperation(RMIConnectionImpl.java:1427)
at javax.management.remote.rmi.RMIConnectionImpl.access$200(RMIConnectionImpl.java:72)
at javax.management.remote.rmi.RMIConnectionImpl$PrivilegedOperation.run(RMIConnectionImpl.java:1265)
at javax.management.remote.rmi.RMIConnectionImpl.doPrivilegedOperation(RMIConnectionImpl.java:1360)
at javax.management.remote.rmi.RMIConnectionImpl.invoke(RMIConnectionImpl.java:788)
at sun.reflect.GeneratedMethodAccessor28.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at sun.rmi.server.UnicastServerRef.dispatch(UnicastServerRef.java:305)
at sun.rmi.transport.Transport$1.run(Transport.java:159)
at java.security.AccessController.doPrivileged(Native Method)
at sun.rmi.transport.Transport.serviceCall(Transport.java:155)
at sun.rmi.transport.tcp.TCPTransport.handleMessages(TCPTransport.java:535)
at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run0(TCPTransport.java:790)
at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(TCPTransport.java:649)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
at java.lang.Thread.run(Thread.java:619)
Caused by: java.lang.ClassCastException: java.util.concurrent.ThreadPoolExecutor cannot be cast to org.apache.cassandra.concurrent.DebuggableThreadPoolExecutor
at org.apache.cassandra.concurrent.DebuggableThreadPoolExecutor$1.rejectedExecution(DebuggableThreadPoolExecutor.java:53)
at java.util.concurrent.ThreadPoolExecutor.reject(ThreadPoolExecutor.java:767)
at java.util.concurrent.ThreadPoolExecutor.execute(ThreadPoolExecutor.java:658)
at java.util.concurrent.AbstractExecutorService.submit(AbstractExecutorService.java:92)
at org.apache.cassandra.db.compaction.ParallelCompactionIterable$Reducer.getCompactedRow(ParallelCompactionIterable.java:211)
at org.apache.cassandra.db.compaction.ParallelCompactionIterable$Reducer.getReduced(ParallelCompactionIterable.java:185)
at org.apache.cassandra.db.compaction.ParallelCompactionIterable$Reducer.getReduced(ParallelCompactionIterable.java:146)
at org.apache.cassandra.utils.ReducingIterator.computeNext(ReducingIterator.java:74)
at com.google.common.collect.AbstractIterator.tryToComputeNext(AbstractIterator.java:140)
at com.google.common.collect.AbstractIterator.hasNext(AbstractIterator.java:135)
at org.apache.cassandra.db.compaction.ParallelCompactionIterable$Unwrapper.computeNext(ParallelCompactionIterable.java:105)
at org.apache.cassandra.db.compaction.ParallelCompactionIterable$Unwrapper.computeNext(ParallelCompactionIterable.java:92)
at com.google.common.collect.AbstractIterator.tryToComputeNext(AbstractIterator.java:140)
at com.google.common.collect.AbstractIterator.hasNext(AbstractIterator.java:135)
at org.apache.commons.collections.iterators.FilterIterator.setNextObject(FilterIterator.java:183)
at org.apache.commons.collections.iterators.FilterIterator.hasNext(FilterIterator.java:94)
at org.apache.cassandra.db.compaction.CompactionManager.doCompactionWithoutSizeEstimation(CompactionManager.java:573)
at org.apache.cassandra.db.compaction.CompactionManager.doCompaction(CompactionManager.java:507)
at org.apache.cassandra.db.compaction.CompactionManager$4.call(CompactionManager.java:320)
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
at java.util.concurrent.FutureTask.run(FutureTask.java:138)
... 3 more