Support RSpec 2 backtrace format

Author: tpope

autoload/rails.vim

@@ -1119,6 +1119,7 @@ let s:efm_backtrace='%D(in\ %f),'
       \.'%\\s%#from\ %f:%l:%m,'
       \.'%\\s%#from\ %f:%l:,'
       \.'%\\s#{RAILS_ROOT}/%f:%l:\ %#%m,'
+      \.'%\\s%##\ %f:%l:%m,'
       \.'%\\s%#[%f:%l:\ %#%m,'
       \.'%\\s%#%f:%l:\ %#%m,'
       \.'%\\s%#%f:%l:,'