NPE in AtomicHashMapDelta.merge caused by TreeCache.put(Fqn, new HashMap())

I tried to test the fix for ISPN-639 and now get a NPE in AtomicHashMapDelta.merge.

2010-09-24 09:16:58,563 ERROR [org.infinispan.remoting.rpc.RpcManagerImpl] (RMI TCP Connection(4)-127.0.0.2) unexpected error while replicating: java.lang.NullPointerException
at org.infinispan.atomic.AtomicHashMapDelta.merge(AtomicHashMapDelta.java:58) [:4.2.0-SNAPSHOT]
at org.infinispan.commands.write.PutKeyValueCommand.perform(PutKeyValueCommand.java:94) [:4.2.0-SNAPSHOT]
at org.infinispan.interceptors.CallInterceptor.handleDefault(CallInterceptor.java:71) [:4.2.0-SNAPSHOT]
.
.
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exception call stack is at http://pastebin.com/ftfm99vW

The code that triggers the NPE originates from a different node than were the replication error occurs:

TreeCache cache = ...
Fqn newf = ...

cache.put(newf, new HashMap<String, Binding>());