Renaming a user to a deleted user fails

Steps to reproduce

1. Create users: UserA and UserB
2. Add UserA to a group 'GroupA'
3. Delete UserB
4. Rename UserA to be UserB
5. It fail with the following errors in atlassian-fisheye-<date>.log:

   2013-03-13 21:26:12,605 WARN  [btpool0-30 ] org.hibernate.util.JDBCExceptionReporter JDBCExceptionReporter-logExceptions - SQL Error: 0, SQLState: null
   2013-03-13 21:26:12,628 ERROR [btpool0-30 ] org.hibernate.util.JDBCExceptionReporter JDBCExceptionReporter-logExceptions - failed batch
   2013-03-13 21:26:12,630 ERROR [btpool0-30 ] org.hibernate.event.def.AbstractFlushingEventListener AbstractFlushingEventListener-performExecutions - Could not synchronize database state with session
   org.hibernate.exception.GenericJDBCException: Could not execute JDBC batch update
   	at org.hibernate.exception.SQLStateConverter.handledNonSpecificException(SQLStateConverter.java:140)
   	at org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:128)
   	at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:66)
   	at org.hibernate.jdbc.AbstractBatcher.executeBatch(AbstractBatcher.java:275)
   	at org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:262)
   	at org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:179)
   	at org.hibernate.event.def.AbstractFlushingEventListener.performExecutions(AbstractFlushingEventListener.java:321)
   ...
   Caused by: java.sql.BatchUpdateException: failed batch
   ...
   2013-03-13 21:26:12,960 ERROR [btpool0-30 ] fisheye TotalityFilter-logExceptionDetails - Exception "org.hibernate.exception.GenericJDBCException: Could not execute JDBC batch update" (javax.servlet.ServletException) while processing "/admin/userRename.do" (Referer:"http://localhost:8060/admin/userRename-default.do")
   javax.servlet.ServletException: org.hibernate.exception.GenericJDBCException: Could not execute JDBC batch update
   	at com.opensymphony.webwork.dispatcher.DispatcherUtils.serviceAction(DispatcherUtils.java:284)
   	at com.opensymphony.webwork.dispatcher.ServletDispatcher.service(ServletDispatcher.java:111)
   	at javax.servlet.http.HttpServlet.service(HttpServlet.java:820)
   	at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:511)
   	at org.mortbay.jetty.servlet.ServletHandler$Chain.doFilter(ServletHandler.java:1272)
   	at com.atlassian.plugin.servlet.filter.IteratingFilterChain.doFilter(IteratingFilterChain.java:46)
   	at com.atlassian.plugin.servlet.filter.DelegatingPluginFilter$1.doFilter(DelegatingPluginFilter.java:66)
   	at com.atlassian.applinks.core.rest.context.ContextFilter.doFilter(ContextFilter.java:25)
   ...
   Caused by: org.hibernate.exception.GenericJDBCException: Could not execute JDBC batch update
   ...
   Caused by: java.sql.BatchUpdateException: failed batch
   ...
   2013-03-13 21:26:12,983 ERROR [btpool0-30 ] org.mortbay.log Slf4jLog-warn - /admin/userRename.do
   org.hibernate.exception.GenericJDBCException: Could not execute JDBC batch update
   	at org.hibernate.exception.SQLStateConverter.handledNonSpecificException(SQLStateConverter.java:140)
   	at org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:128)
   	at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:66)
   	at org.hibernate.jdbc.AbstractBatcher.executeBatch(AbstractBatcher.java:275)
   	at org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:262)
   	at org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:179)
   	at org.hibernate.event.def.AbstractFlushingEventListener.performExecutions(AbstractFlushingEventListener.java:321)
   ...
   Caused by: java.sql.BatchUpdateException: failed batch
   

6. Check the group that belongs to UserA