24.3.50; cperl-mode + which-function: Inaccurate reporting (corner case)

See the attached screenshot.  Note the following

1. Cursor position in the top window. 

   In the bottom window, the cursor is well within the toplevel block of
   sub.

2. which-function field of the modeline.

Hint: Note the presence/absence of `=' (most likely from the =cut line above)