We currently have no plans to pursue this, so I'm closing the issue. Feel free to reopen it when you want to work on this.

To let a search exit immediately, you can use bound=0.

We would like to add a max_expansions parameter to the searches (similarly to the max_time 
parameter). This would allow us compare heuristics by measuring the lower bounds they can 
prove with a fixed amount of expansions. Also, by setting max_expansions=0 we could prevent 
the planner from doing any search, effectively eliminating the need for M&S's `terminate` 
argument.