The signaling of a sub process has been changed with JBPM-2948, contradicting the synchronous signaling behavior of jBPM as described in Section 6.11 of the jBPM Reference Guide:
"...the process in the thread of the client and is, by nature, synchronous. In practice, this means that the token.signal() or taskInstance.end() will only return when the process has entered a new wait state."
http://docs.redhat.com/docs/en-US/JBoss_Enterprise_SOA_Platform/5/html/JBPM_Reference_Guide/transactiondemarcation.html

Moreover, it leads to a different result in case of a rollback.

The intent of this JIRA is to add a configuration switch to enable asynchronous sub-process signaling as introduced with JBPM-2948, and revert the default signaling mode to be synchronous as before.