Upgrade Tasks fail when thumbnails have special characters

2011-06-29 08:52:22,840 DEBUG [main] [springframework.orm.hibernate.HibernateTransactionManager] doCleanupAfterCompletion Closing Hibernate Session [net.sf.hibernate.impl.SessionImpl@62ecd2de] after transaction
2011-06-29 08:52:22,841 DEBUG [main] [springframework.orm.hibernate.SessionFactoryUtils] closeSession Closing Hibernate Session
2011-06-29 08:52:22,841 DEBUG [main] [mchange.v2.resourcepool.BasicResourcePool] trace trace com.mchange.v2.resourcepool.BasicResourcePool@76f4da6d [managed: 1, unused: 0, excluded: 0] (e.g. com.mchange.v2.c3p0.impl.NewPooledConnection@43794494)
2011-06-29 08:52:23,054 DEBUG [main] [atlassian.johnson.config.JohnsonConfig] configureEventChecks Adding eventcheck of class: com.atlassian.confluence.setup.johnson.WebAppContextPathCheck
2011-06-29 08:52:23,060 ERROR [main] [atlassian.confluence.upgrade.UpgradeLauncherServletContextListener] contextInitialized Upgrade failed, application will not start: Upgrade task failed: class com.atlassian.confluence.upgrade.upgradetask.PurgeThumbnailsUpgradeTask
com.atlassian.confluence.upgrade.UpgradeException: Upgrade task failed: class com.atlassian.confluence.upgrade.upgradetask.PurgeThumbnailsUpgradeTask
        at com.atlassian.confluence.upgrade.AbstractUpgradeManager.doUpgrade(AbstractUpgradeManager.java:213)
        at com.atlassian.confluence.upgrade.AbstractUpgradeManager.upgrade(AbstractUpgradeManager.java:92)
        at com.atlassian.confluence.upgrade.impl.DefaultUpgradeManager.upgrade(DefaultUpgradeManager.java:139)
        at com.atlassian.confluence.upgrade.UpgradeLauncherServletContextListener.contextInitialized(UpgradeLauncherServletContextListener.java:28)
        at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4205)
        at org.apache.catalina.core.StandardContext.start(StandardContext.java:4704)
        at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1053)
        at org.apache.catalina.core.StandardHost.start(StandardHost.java:840)
        at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1053)
        at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:463)
        at org.apache.catalina.core.StandardService.start(StandardService.java:525)
        at org.apache.catalina.core.StandardServer.start(StandardServer.java:754)
        at org.apache.catalina.startup.Catalina.start(Catalina.java:595)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:597)
        at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:289)
        at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:414)
2011-06-29 08:52:23,083 ERROR [main] [atlassian.confluence.upgrade.UpgradeLauncherServletContextListener] contextInitialized 1 errors were encountered during upgrade:
2011-06-29 08:52:23,084 ERROR [main] [atlassian.confluence.upgrade.UpgradeLauncherServletContextListener] contextInitialized 1: Error removing thumbnails directory [/home/confluence-upgrade/intern/thumbnails] from confluence home
2011-06-29 08:52:23,084 DEBUG [main] [atlassian.confluence.setup.ConfluenceListableBeanFactory] getBean Returning cached instance of singleton bean 'lifecycleManager'
2011-06-29 08:52:23,085 DEBUG [main] [springframework.orm.hibernate.HibernateTransactionManager] getTransaction Using transaction object [org.springframework.orm.hibernate.HibernateTransactionManager$HibernateTransactionObject@279e5431]
2011-06-29 08:52:23,086 DEBUG [main] [springframework.orm.hibernate.HibernateTransactionManager] getTransaction Creating new transaction with name [com.atlassian.event.EventManager.publishEvent]: PROPAGATION_REQUIRED,ISOLATION_DEFAULT
2011-06-29 08:52:23,086 DEBUG [main] [springframework.orm.hibernate.HibernateTransactionManager] doBegin Opened new Session [net.sf.hibernate.impl.SessionImpl@ba97149] for Hibernate transaction