Hmmm, that was a problem with the old Petri net based workflow package, too ... we dumped Petri nets in favor of FSMs but this particular problem still remains.
At the moment sticking in the explicit rollback transitions in the FSM is the only way to do this.
How far back do you want to go? The "start" state?
I suppose we could allow one to optionally mark a state as being "always enabled" ...
It's not nearly as bad with FSMs at least as it was with the Petri net implementation, though, in the latter case you have to make sure the right number of and combinations of tokens are generated and consumed as well as add all the transitions.
