Editing user and setting Source Repository Alias causes null pointer exception

assigning a repository alias to an external (ldap) user throws NPE

2010-01-14 14:41:36,093 ERROR [4844447@qtp-6659511-0] [FiveOhOh] 500 Exception was thrown.
java.lang.NullPointerException
at java.util.AbstractCollection.addAll(AbstractCollection.java:316)
at com.atlassian.bamboo.ww2.actions.admin.user.ConfigureUser.execute(ConfigureUser.java:88)
at com.atlassian.bamboo.ww2.actions.admin.user.ConfigureUser.doUpdateExternalUser(ConfigureUser.java:153)
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:592)