Note that the first commit changes the behavior of the matcher a bit; before it swallowed all exceptions, which I felt was a bug. Since there's a slight chance this could break someone's specs, you might consider putting that commit in master but not the 2-0 stable branch.
Improve failure messages for throw_symbol matcher and add a cuke for it.
Fix throw_symbol matcher so that it no longer swallows exceptions tha…
…t occur in the proc.