Confluence attempts to apply group memberships when synchronising from a remote directory even if they already exist, causing a duplicate key violation

2013-02-21 09:59:32,590 ERROR [scheduler_Worker-2] [atlassian.crowd.directory.DbCachingDirectoryPoller] pollChanges Error occurred while refreshing the cache for directory [ 98307 ].
org.springframework.dao.DataIntegrityViolationException: Hibernate operation: could not insert: [com.atlassian.crowd.embedded.hibernate2.HibernateMembership#295380]; SQL []; ERROR: duplicate key value violates unique constraint "cwd_unique_user_membership"
  Detail: Key (parent_id, child_user_id)=(163849, 229382) already exists.; nested exception is org.postgresql.util.PSQLException: ERROR: duplicate key value violates unique constraint "cwd_unique_user_membership"
  Detail: Key (parent_id, child_user_id)=(163849, 229382) already exists.
	at org.springframework.jdbc.support.SQLStateSQLExceptionTranslator.doTranslate(SQLStateSQLExceptionTranslator.java:100)
	at org.springframework.jdbc.support.AbstractFallbackSQLExceptionTranslator.translate(AbstractFallbackSQLExceptionTranslator.java:72)
	at org.springframework.orm.hibernate.HibernateTransactionManager.convertJdbcAccessException(HibernateTransactionManager.java:619)
	at org.springframework.orm.hibernate.HibernateTransactionManager.convertHibernateAccessException(HibernateTransactionManager.java:605)
	at org.springframework.orm.hibernate.HibernateTransactionManager.doCommit(HibernateTransactionManager.java:518)
	at org.springframework.transaction.support.AbstractPlatformTransactionManager.processCommit(AbstractPlatformTransactionManager.java:732)
	at org.springframework.transaction.support.AbstractPlatformTransactionManager.commit(AbstractPlatformTransactionManager.java:701)
	at org.springframework.transaction.interceptor.TransactionAspectSupport.commitTransactionAfterReturning(TransactionAspectSupport.java:321)
	at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:116)
	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:171)
	at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:204)
	at com.atlassian.crowd.directory.$Proxy1476.addUserToGroup(Unknown Source)
	at com.atlassian.crowd.directory.DirectoryCacheImplUsingChangeOperations.addUserToGroup(DirectoryCacheImplUsingChangeOperations.java:187)
	at com.atlassian.crowd.directory.ldap.cache.EventTokenChangedCacheRefresher.synchroniseChanges(EventTokenChangedCacheRefresher.java:115)
	at com.atlassian.crowd.directory.DbCachingRemoteDirectory.synchroniseCache(DbCachingRemoteDirectory.java:610)
	at com.atlassian.crowd.manager.directory.DirectorySynchroniserImpl.synchronise(DirectorySynchroniserImpl.java:63)
	at com.atlassian.crowd.directory.DbCachingDirectoryPoller.pollChanges(DbCachingDirectoryPoller.java:50)
	at com.atlassian.crowd.manager.directory.monitor.poller.DirectoryPollerJobBean.executeInternal(DirectoryPollerJobBean.java:29)
	at org.springframework.scheduling.quartz.QuartzJobBean.execute(QuartzJobBean.java:86)
	at org.quartz.core.JobRunShell.run(JobRunShell.java:199)
	at com.atlassian.confluence.schedule.quartz.ConfluenceQuartzThreadPool$1.run(ConfluenceQuartzThreadPool.java:20)
	at org.quartz.simpl.SimpleThreadPool$WorkerThread.run(SimpleThreadPool.java:549)
Caused by: org.postgresql.util.PSQLException: ERROR: duplicate key value violates unique constraint "cwd_unique_user_membership"
  Detail: Key (parent_id, child_user_id)=(163849, 229382) already exists.
	at org.postgresql.core.v3.QueryExecutorImpl.receiveErrorResponse(QueryExecutorImpl.java:2102)
	at org.postgresql.core.v3.QueryExecutorImpl.processResults(QueryExecutorImpl.java:1835)
	at org.postgresql.core.v3.QueryExecutorImpl.execute(QueryExecutorImpl.java:257)
	at org.postgresql.jdbc2.AbstractJdbc2Statement.execute(AbstractJdbc2Statement.java:500)
	at org.postgresql.jdbc2.AbstractJdbc2Statement.executeWithFlags(AbstractJdbc2Statement.java:388)
	at org.postgresql.jdbc2.AbstractJdbc2Statement.executeUpdate(AbstractJdbc2Statement.java:334)
	at com.mchange.v2.c3p0.impl.NewProxyPreparedStatement.executeUpdate(NewProxyPreparedStatement.java:105)
	at net.sf.hibernate.impl.NonBatchingBatcher.addToBatch(NonBatchingBatcher.java:22)
	at net.sf.hibernate.persister.EntityPersister.insert(EntityPersister.java:462)
	at net.sf.hibernate.persister.EntityPersister.insert(EntityPersister.java:436)
	at net.sf.hibernate.impl.ScheduledInsertion.execute(ScheduledInsertion.java:37)
	at net.sf.hibernate.impl.SessionImpl.execute(SessionImpl.java:2464)
	at net.sf.hibernate.impl.SessionImpl.executeAll(SessionImpl.java:2450)
	at net.sf.hibernate.impl.SessionImpl.execute(SessionImpl.java:2407)
	at net.sf.hibernate.impl.SessionImpl.flush(SessionImpl.java:2276)
	at net.sf.hibernate.transaction.JDBCTransaction.commit(JDBCTransaction.java:61)
	at org.springframework.orm.hibernate.HibernateTransactionManager.doCommit(HibernateTransactionManager.java:510)
	... 17 more