Backtrace for passing specs


I’m using example.implementation_backtrace in a custom formatter to
get the path of the file a passing spec belongs to. Following rspec on
github I saw that implementation_backtrace is now deprecated and
replaced by example.backtrace. Sadly it always returns nil for passed
specs. So I had a look at the source and found that backtrace only
gets assigned if line_number was set.

Can anybody tell me why this was changed to only work with line_number
set and if there is another way to get the file a spec belongs to.

Thanks for your help!

lg // andreas