GhUpgradeTask032 failed due to NPE

2013-03-21 07:45:07,751 http-apr-8080-exec-15 ERROR vkharisma@awesome.com 465x1147x1 12tabsn 172.21.140.111 /rest/plugins/1.0/com.pyxis.greenhopper.jira-key [sal.core.upgrade.DefaultPluginUpgradeManager] Upgrade error: Unexpected exception caught during plugin upgrade: java.lang.NullPointerException
	at com.atlassian.crowd.embedded.impl.IdentifierUtils.toLowerCase(IdentifierUtils.java:42)
	at com.atlassian.greenhopper.upgrade.GhUpgradeTask032DaoImpl.processCardColor(GhUpgradeTask032DaoImpl.java:67)
	at com.atlassian.greenhopper.upgrade.GhUpgradeTask032DaoImpl.access$100(GhUpgradeTask032DaoImpl.java:15)
	at com.atlassian.greenhopper.upgrade.GhUpgradeTask032DaoImpl$2.onRowRead(GhUpgradeTask032DaoImpl.java:55)
	at com.atlassian.greenhopper.upgrade.GhUpgradeTask032DaoImpl$2.onRowRead(GhUpgradeTask032DaoImpl.java:51)
	at net.java.ao.EntityManager.stream(EntityManager.java:924)

          ...
          // make it lower case - we hope "unassigned" is already ok...
          String assignee = cardColorAO.getVal();
          String lowercasedAssignee = IdentifierUtils.toLowerCase(assignee);
          if(!assignee.equals(lowercasedAssignee))
          {
              cardColorAO = ao.get(CardColorAO.class, cardColorAO.getId());
              logInfo("Changing card color assignee from '%s' to '%s'", assignee, lowercasedAssignee);
              cardColorAO.setVal(lowercasedAssignee);
              cardColorAO.save();
          ...