Comment 1 for bug 2016417

This is because + is source transformed and loses its source location. This has always been the case. At least now
(block nil
  (return)
  (+ 1 2 3))
signals a note by attaching the source location to the starting ctran, but in the (+ 1 2 (return)) case the initial ctran gets executed and there's no good place to attach a source path.