Permission scheme page fails when the username is renamed

Steps to reproduce:

1. Set an individual user to the permission scheme e.g the "Edit Review Details"
   
2. Rename the username via Administration > Users
3. Edit the permission schemes again leads to the following errors:

   2010-02-22 16:06:46,375 ERROR [btpool0-2] com.opensymphony.xwork.util.CompoundRootAccessor com.opensymphony.xwork.util.CompoundRootAccessor-getProperty - Caught an Ognl exception while getting property actions
   ognl.OgnlException: actions [java.lang.IllegalArgumentException: No such user:nick]
   
   	at ognl.OgnlRuntime.getMethodValue(OgnlRuntime.java:1416)
   
   	at ognl.ObjectPropertyAccessor.getPossibleProperty(ObjectPropertyAccessor.java:60)
   
   	at ognl.ObjectPropertyAccessor.getProperty(ObjectPropertyAccessor.java:147)
   
   	at com.opensymphony.xwork.util.OgnlValueStack$ObjectAccessor.getProperty(OgnlValueStack.java:57)
   
   	at ognl.OgnlRuntime.getProperty(OgnlRuntime.java:2210)
   
   	at com.opensymphony.xwork.util.CompoundRootAccessor.getProperty(CompoundRootAccessor.java:102)
   
   	at ognl.OgnlRuntime.getProperty(OgnlRuntime.java:2210)
   
   	at ognl.ASTProperty.getValueBody(ASTProperty.java:114)
   
   ...
   Caused by: java.lang.IllegalArgumentException: No such user:nick
   
   	at com.atlassian.crucible.spi.impl.Utils.getUserByName(Utils.java:60)
   
   	at com.atlassian.crucible.spi.impl.Utils.getUserByName(Utils.java:67)
   
   	at com.cenqua.crucible.actions.admin.permschemes.ActionData.addUser(ActionData.java:82)
   
   	at com.cenqua.crucible.actions.admin.permschemes.EditPermSchemeAction.mapPsActions(EditPermSchemeAction.java:71)
   
   	at com.cenqua.crucible.actions.admin.permschemes.EditPermSchemeAction.getActions(EditPermSchemeAction.java:50)
   
   	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)
   
   

4. Permission schemes page is broken. See permission-schemes.png