Delayed deletion is unable to delete stages

2011-10-05 01:18:18,932 DEBUG [QuartzScheduler_Worker-6] [DeletionServiceImpl] Starting background deletion
2011-10-05 01:18:19,132 INFO [QuartzScheduler_Worker-6] [DeletionServiceImpl] Deleting 13 stage(s) marked for deletion
2011-10-05 01:18:19,132 INFO [QuartzScheduler_Worker-6] [DeletionServiceImpl] Deleting stage Default Stage from THESINK-FUNC
2011-10-05 01:18:20,172 INFO [QuartzScheduler_Worker-4] [ElasticRunningInstancesOptimizerImpl] Currently there are no agents that can build: BDT-MYSQL-JOB1, BDT-ORACLE-JOB1, BDT-PGQSL-JOB1. New elastic instance(s) will be started (providing the configuration allows it).
2011-10-05 01:18:20,847 INFO [elastic-pool-3-thread-10] [request] Sending Request: POST https://ec2.amazonaws.com / Parameters: (Action: DescribeInstances, SignatureMethod: HmacSHA256, AWSAccessKeyId: AKIAJIVXVTXEYQ32ZNPA, Version: 2010-08-31, SignatureVersion: 2, Timestamp: 2011-10-04T14:18:20.842Z, Signature: OmyfkAu5rPh0HlefLgyZTaSHqPepdXYvmmKAkARXW7E=, ) 
2011-10-05 01:18:21,906 INFO [elastic-pool-3-thread-10] [request] Received successful response: 200, AWS Request ID: 3121d009-2870-49bb-ada3-ceb687dbef8d
2011-10-05 01:18:22,404 ERROR [QuartzScheduler_Worker-6] [JobRunShell] Job Plan Deletion Service Group.Plan Deletion Job threw an unhandled Exception: 
org.springframework.orm.hibernate.HibernateSystemException: a different object with the same identifier value was already associated with the session: 15728644, of class: com.atlassian.bamboo.notification.NotificationSetImpl; nested exception is net.sf.hibernate.NonUniqueObjectException: a different object with the same identifier value was already associated with the session: 15728644, of class: com.atlassian.bamboo.notification.NotificationSetImpl
Caused by: net.sf.hibernate.NonUniqueObjectException: a different object with the same identifier value was already associated with the session: 15728644, of class: com.atlassian.bamboo.notification.NotificationSetImpl
        at net.sf.hibernate.impl.SessionImpl.checkUniqueness(SessionImpl.java:1685)
        at net.sf.hibernate.impl.SessionImpl.doUpdateMutable(SessionImpl.java:1451)
        at net.sf.hibernate.impl.SessionImpl.doUpdate(SessionImpl.java:1478)
        at net.sf.hibernate.impl.SessionImpl.saveOrUpdate(SessionImpl.java:1401)
        at net.sf.hibernate.engine.Cascades$4.cascade(Cascades.java:114)
        at net.sf.hibernate.engine.Cascades.cascade(Cascades.java:436)
        at net.sf.hibernate.engine.Cascades.cascade(Cascades.java:503)
        at net.sf.hibernate.engine.Cascades.cascade(Cascades.java:482)
        at net.sf.hibernate.impl.SessionImpl.doUpdate(SessionImpl.java:1483)
        at net.sf.hibernate.impl.SessionImpl.saveOrUpdate(SessionImpl.java:1401)
        at org.springframework.orm.hibernate.HibernateTemplate$12.doInHibernate(HibernateTemplate.java:604)
        at org.springframework.orm.hibernate.HibernateTemplate.execute(HibernateTemplate.java:370)
        at org.springframework.orm.hibernate.HibernateTemplate.saveOrUpdate(HibernateTemplate.java:601)
        at com.atlassian.bamboo.persistence3.BambooHibernateObjectDao.save(BambooHibernateObjectDao.java:34)
        at com.atlassian.bamboo.plan.PlanHibernateDao.save(PlanHibernateDao.java:308)
        at com.atlassian.bamboo.plan.PlanHibernateDao.save(PlanHibernateDao.java:28)
        at sun.reflect.GeneratedMethodAccessor633.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:597)
        at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:304)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:182)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:149)
        at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:106)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:171)
        at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:204)
        at $Proxy2.save(Unknown Source)
        at com.atlassian.bamboo.plan.PlanManagerImpl.savePlan(PlanManagerImpl.java:258)
        at sun.reflect.GeneratedMethodAccessor1120.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:597)
        at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:304)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:182)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:149)
        at com.atlassian.bamboo.security.acegi.intercept.aopalliance.AuthorityOverrideMethodSecurityInterceptor.invoke(AuthorityOverrideMethodSecurityInterceptor.java:29)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:171)
        at com.atlassian.bamboo.security.acegi.intercept.aopalliance.AuthorityOverrideMethodSecurityInterceptor.invoke(AuthorityOverrideMethodSecurityInterceptor.java:29)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:171)
        at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:106)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:171)
        at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:106)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:171)
        at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:204)
        at $Proxy11.savePlan(Unknown Source)
        at com.atlassian.bamboo.deletion.DeletionServiceImpl.executeDelayedDeletion(DeletionServiceImpl.java:236)
        at sun.reflect.GeneratedMethodAccessor1077.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:597)
        at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:304)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:182)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:149)
        at com.atlassian.bamboo.security.acegi.intercept.aopalliance.AuthorityOverrideMethodSecurityInterceptor.invoke(AuthorityOverrideMethodSecurityInterceptor.java:29)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:171)
        at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:204)
        at $Proxy70.executeDelayedDeletion(Unknown Source)
        at com.atlassian.bamboo.deletion.DeletionServiceJob.execute(DeletionServiceJob.java:26)
        at org.quartz.core.JobRunShell.run(JobRunShell.java:202)
        at com.atlassian.bamboo.quartz.SystemAuthorizedThreadPool$1.run(SystemAuthorizedThreadPool.java:38)
        at org.quartz.simpl.SimpleThreadPool$WorkerThread.run(SimpleThreadPool.java:525)