java.lang.Boolean cannot be cast to org.drools.spi.Activation when used incremental kAgent + accumulate

When used accumulate and incremental changes from the kagent (drools.agent.newInstance as false)the exception below is throwed:

Exception in thread "Thread-0" java.lang.ClassCastException:
java.lang.Boolean cannot be cast to org.drools.spi.Activation
at org.drools.reteoo.RuleTerminalNode$RTNCleanupAdapter.cleanUp(RuleTerminalNode.java:492)
at org.drools.reteoo.BetaNode.doRemove(BetaNode.java:381)
at org.drools.common.BaseNode.remove(BaseNode.java:105)
at org.drools.reteoo.RuleTerminalNode.doRemove(RuleTerminalNode.java:367)
at org.drools.common.BaseNode.remove(BaseNode.java:105)

Unit test attached.