NPE when expiring a build result

2013-07-26 00:51:13,278 WARN [QuartzScheduler_Worker-4] [BuildExpiryBean] Unable to expire BAM-FC-10239
java.lang.NullPointerException
	at com.atlassian.bamboo.build.artifact.DefaultArtifactLink.isSharedArtifact(DefaultArtifactLink.java:203)
	at com.atlassian.bamboo.build.artifact.ArtifactLinkPredicates$ArtifactLinkIsSharedArtifactPredicate.apply(ArtifactLinkPredicates.java:89)
	at com.atlassian.bamboo.build.artifact.ArtifactLinkPredicates$ArtifactLinkIsSharedArtifactPredicate.apply(ArtifactLinkPredicates.java:83)
	at com.google.common.base.Predicates$NotPredicate.apply(Predicates.java:308)
	at com.google.common.collect.Iterators.removeIf(Iterators.java:213)
	at com.google.common.collect.Iterables.removeIf(Iterables.java:184)
	at com.atlassian.bamboo.build.artifact.DefaultArtifactLinkManager.removeArtifactLinks(DefaultArtifactLinkManager.java:176)
	at com.atlassian.bamboo.resultsummary.BuildResultsSummaryManagerImpl.removeArtifacts(BuildResultsSummaryManagerImpl.java:1013)
	at sun.reflect.GeneratedMethodAccessor2501.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
	at java.lang.reflect.Method.invoke(Method.java:597)
	at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:304)
	at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:182)
	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:149)
	at com.atlassian.bamboo.security.acegi.intercept.aopalliance.AuthorityOverrideMethodSecurityInterceptor.invoke(AuthorityOverrideMethodSecurityInterceptor.java:29)
	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:171)
	at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:106)
	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:171)
	at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:204)
	at com.sun.proxy.$Proxy50.removeArtifacts(Unknown Source)
	at com.atlassian.bamboo.build.expiry.BuildExpiryBean.expirePlan(BuildExpiryBean.java:267)
	at com.atlassian.bamboo.build.expiry.BuildExpiryBean.expireAllBuilds(BuildExpiryBean.java:128)
	at com.atlassian.bamboo.build.expiry.BuildExpiryScheduler$BuildExpiryJob.execute(BuildExpiryScheduler.java:113)
	at org.quartz.core.JobRunShell.run(JobRunShell.java:202)
	at com.atlassian.bamboo.quartz.SystemAuthorizedThreadPool$1.run(SystemAuthorizedThreadPool.java:38)