Crowd synchronization can fail processing groups

2014-11-18 06:41:59,215 ERROR [clusterScheduler_Worker-5]  c.a.c.u.p.h.b.AbstractBatchProcessor Could not process class com.atlassian.crowd.model.group.InternalGroup: com.atlassian.crowd.model.group.InternalGroup@eeac4af[id=11599873,name=name-name-name,type=GROUP,active=true,description=Some description,lowerName=name-name-name,createdDate=2014-11-12 22:46:08.32,updatedDate=2014-11-12 23:46:08.798,directoryId=32770]
org.hibernate.HibernateException: Illegal attempt to associate a collection with two open sessions
        at org.hibernate.collection.internal.AbstractPersistentCollection.setCurrentSession(AbstractPersistentCollection.java:633) ~[AbstractPersistentCollection.class:4.3.6.Final]
        at org.hibernate.event.internal.OnUpdateVisitor.processCollection(OnUpdateVisitor.java:63) ~[OnUpdateVisitor.class:4.3.6.Final]
        at org.hibernate.event.internal.AbstractVisitor.processValue(AbstractVisitor.java:121) ~[AbstractVisitor.class:4.3.6.Final]
        at org.hibernate.event.internal.AbstractVisitor.processValue(AbstractVisitor.java:82) ~[AbstractVisitor.class:4.3.6.Final]
        at org.hibernate.event.internal.AbstractVisitor.processEntityPropertyValues(AbstractVisitor.java:76) ~[AbstractVisitor.class:4.3.6.Final]
        at org.hibernate.event.internal.AbstractVisitor.process(AbstractVisitor.java:143) ~[AbstractVisitor.class:4.3.6.Final]
        at org.hibernate.event.internal.DefaultDeleteEventListener.onDelete(DefaultDeleteEventListener.java:120) ~[DefaultDeleteEventListener.class:4.3.6.Final]
        at org.hibernate.event.internal.DefaultDeleteEventListener.onDelete(DefaultDeleteEventListener.java:73) ~[DefaultDeleteEventListener.class:4.3.6.Final]
        at org.hibernate.internal.SessionImpl.fireDelete(SessionImpl.java:920) ~[SessionImpl.class:4.3.6.Final]
        at org.hibernate.internal.SessionImpl.delete(SessionImpl.java:896) ~[SessionImpl.class:4.3.6.Final]
        at com.atlassian.crowd.util.persistence.hibernate.batch.hibernate4.operation.RemoveGroupOperation.performOperation(RemoveGroupOperation.java:43) ~[RemoveGroupOperation.class:na]
        at com.atlassian.crowd.util.persistence.hibernate.batch.hibernate4.operation.RemoveGroupOperation.performOperation(RemoveGroupOperation.java:17) ~[RemoveGroupOperation.class:na]
        at com.atlassian.crowd.util.persistence.hibernate.batch.AbstractBatchProcessor.performOperation(AbstractBatchProcessor.java:212) [AbstractBatchProcessor.class:na]
        at com.atlassian.crowd.util.persistence.hibernate.batch.AbstractBatchProcessor.processIndividual(AbstractBatchProcessor.java:184) [AbstractBatchProcessor.class:na]
        at com.atlassian.crowd.util.persistence.hibernate.batch.AbstractBatchProcessor.processBatch(AbstractBatchProcessor.java:168) [AbstractBatchProcessor.class:na]
        at com.atlassian.crowd.util.persistence.hibernate.batch.AbstractBatchProcessor.execute(AbstractBatchProcessor.java:133) [AbstractBatchProcessor.class:na]
        at com.atlassian.crowd.dao.group.GroupDAOHibernate.removeAllGroups(GroupDAOHibernate.java:237) [GroupDAOHibernate.class:na]
        at com.atlassian.crowd.directory.AbstractInternalDirectory.removeAllGroups(AbstractInternalDirectory.java:767) [AbstractInternalDirectory.class:na]
        at com.atlassian.crowd.directory.DbCachingRemoteChangeOperations.deleteCachedGroups(DbCachingRemoteChangeOperations.java:690) [DbCachingRemoteChangeOperations.class:na]
        at com.atlassian.crowd.directory.DbCachingRemoteChangeOperations.deleteCachedGroupsNotIn(DbCachingRemoteChangeOperations.java:679) [DbCachingRemoteChangeOperations.class:na]
        at com.atlassian.crowd.directory.$Proxy1997.deleteCachedGroupsNotIn(Unknown Source) [na:na]
        at com.atlassian.crowd.directory.DirectoryCacheImplUsingChangeOperations.deleteCachedGroupsNotIn(DirectoryCacheImplUsingChangeOperations.java:99) [DirectoryCacheImplUsingChangeOperations.class:na]
        at com.atlassian.crowd.directory.ldap.cache.RemoteDirectoryCacheRefresher.synchroniseAllGroups(RemoteDirectoryCacheRefresher.java:113) [RemoteDirectoryCacheRefresher.class:na]
        at com.atlassian.crowd.directory.ldap.cache.AbstractCacheRefresher.synchroniseAll(AbstractCacheRefresher.java:82) [AbstractCacheRefresher.class:na]
        at com.atlassian.crowd.directory.ldap.cache.EventTokenChangedCacheRefresher.synchroniseAll(EventTokenChangedCacheRefresher.java:66) [EventTokenChangedCacheRefresher.class:na]
        at com.atlassian.crowd.directory.DbCachingRemoteDirectory.synchroniseCache(DbCachingRemoteDirectory.java:1120) [DbCachingRemoteDirectory.class:na]
        at com.atlassian.crowd.manager.directory.DirectorySynchroniserImpl.synchronise(DirectorySynchroniserImpl.java:76) [DirectorySynchroniserImpl.class:na]