Intermittent problem encountered when building projects with distributed builds

2011-08-05 14:00:00,525 [pool-9-thread-1] ERROR org.apache.continuum.builder.distributed.executor.DistributedBuildProjectTaskExecutor - Error occurred while building task
java.lang.Exception: Failed to build projects in build agent http://localhost:8181/continuum-buildagent/xmlrpc
at org.apache.continuum.distributed.transport.slave.SlaveBuildAgentTransportClient.buildProjects(SlaveBuildAgentTransportClient.java:92)
at org.apache.continuum.builder.distributed.executor.DistributedBuildProjectTaskExecutor.executeTask(DistributedBuildProjectTaskExecutor.java:121)
at org.apache.continuum.builder.distributed.executor.ThreadedDistributedBuildTaskQueueExecutor$ExecutorRunnable$1.run(ThreadedDistributedBuildTaskQueueExecutor.java:118)
at edu.emory.mathcs.backport.java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:442)
at edu.emory.mathcs.backport.java.util.concurrent.FutureTask.run(FutureTask.java:176)
at edu.emory.mathcs.backport.java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:987)
at edu.emory.mathcs.backport.java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:528)
at java.lang.Thread.run(Thread.java:680)
Caused by: java.lang.RuntimeException: Could not execute RPC method buildProjects
at com.atlassian.xmlrpc.XmlRpcInvocationHandler.invoke(XmlRpcInvocationHandler.java:163)
at $Proxy12.buildProjects(Unknown Source)
at org.apache.continuum.distributed.transport.slave.SlaveBuildAgentTransportClient.buildProjects(SlaveBuildAgentTransportClient.java:86)
... 7 more
Caused by: java.lang.NullPointerException
at java.util.GregorianCalendar.computeFields(GregorianCalendar.java:2026)
at java.util.GregorianCalendar.computeFields(GregorianCalendar.java:1996)
at java.util.Calendar.setTimeInMillis(Calendar.java:1109)
at java.util.GregorianCalendar.<init>(GregorianCalendar.java:576)
at java.util.Calendar.createCalendar(Calendar.java:1011)
at java.util.Calendar.getInstance(Calendar.java:963)
at org.apache.xmlrpc.util.XmlRpcDateTimeDateFormat.format(XmlRpcDateTimeDateFormat.java:37)
at java.text.Format.format(Format.java:140)
at org.apache.xmlrpc.serializer.DateSerializer.write(DateSerializer.java:43)
at org.apache.xmlrpc.serializer.MapSerializer.writeValue(MapSerializer.java:77)
at org.apache.xmlrpc.serializer.MapSerializer.writeEntry(MapSerializer.java:67)
at org.apache.xmlrpc.serializer.MapSerializer.writeData(MapSerializer.java:84)
at org.apache.xmlrpc.serializer.MapSerializer.write(MapSerializer.java:91)
at org.apache.xmlrpc.serializer.ObjectArraySerializer.writeObject(ObjectArraySerializer.java:53)
at org.apache.xmlrpc.serializer.ObjectArraySerializer.writeData(ObjectArraySerializer.java:58)
at org.apache.xmlrpc.serializer.ObjectArraySerializer.write(ObjectArraySerializer.java:65)
at org.apache.xmlrpc.serializer.XmlRpcWriter.writeValue(XmlRpcWriter.java:175)
at org.apache.xmlrpc.serializer.XmlRpcWriter.write(XmlRpcWriter.java:80)
at org.apache.xmlrpc.client.XmlRpcStreamTransport$ReqWriterImpl.write(XmlRpcStreamTransport.java:70)
at org.apache.xmlrpc.client.XmlRpcHttpTransport$ByteArrayReqWriter.<init>(XmlRpcHttpTransport.java:41)
at org.apache.xmlrpc.client.XmlRpcHttpTransport.newReqWriter(XmlRpcHttpTransport.java:127)
at org.apache.xmlrpc.client.XmlRpcStreamTransport.sendRequest(XmlRpcStreamTransport.java:150)
at org.apache.xmlrpc.client.XmlRpcHttpTransport.sendRequest(XmlRpcHttpTransport.java:115)
at org.apache.xmlrpc.client.XmlRpcClientWorker.execute(XmlRpcClientWorker.java:56)
at org.apache.xmlrpc.client.XmlRpcClient.execute(XmlRpcClient.java:167)
at org.apache.xmlrpc.client.XmlRpcClient.execute(XmlRpcClient.java:158)
at org.apache.xmlrpc.client.XmlRpcClient.execute(XmlRpcClient.java:147)
at com.atlassian.xmlrpc.ApacheBinder$1.execute(ApacheBinder.java:64)
at com.atlassian.xmlrpc.XmlRpcInvocationHandler.invoke(XmlRpcInvocationHandler.java:151)
... 9 more