When a node receives a heartbeat containing a recipient config, it first checks if the config is valid. A few lines later we print out a warning and bail early if the validation produces a non-OK status. The replication coordinator state when performing this validation is kConfigHBReconfiguring, and bailing early in this case fails to transition the state back to a state which could accept future reconfigs. The effect is that once a node fails this validation, it can no longer receive additional reconfigs in the future.