Rank field migration divides by zero

2011-10-19 16:38:28,718 main ERROR [sal.core.upgrade.PluginUpgrader] Upgrade failed: / by zero
java.lang.ArithmeticException: / by zero
at com.atlassian.greenhopper.upgrade.GhUpgradeTask012Dao.migrate(GhUpgradeTask012Dao.java:50)
at com.atlassian.greenhopper.upgrade.GhUpgradeTask012.performUpgrade(GhUpgradeTask012.java:35)
at com.atlassian.greenhopper.upgrade.AbstractGhUpgradeTask.doUpgrade(AbstractGhUpgradeTask.java:46)
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.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:307)