PR: MNG-1311 Added a stack of lifecycle fork-points that will be removed from each successively deeper level of forking in a cumulative manner, to prevent multi-node cycles in addition to simply blocking two-node cycles. The basic problem with the recursion check that was in there was a type mismatch on the contents of a java.util.List. It's fixed now.
maven/components/trunk/maven-core/src/main/java/org/apache/maven/lifecycle/DefaultLifecycleExecutor.java