I'd call it a bug, unless of course it's just poetry mode in action. But that would be a bug too, becuase you have struct 'subs' in effect. OK, it's a bug.
A bug as in "too bad perl implemented it that way" or as in "time to dig into regcomp.c and whip out perlbug." Would you categorize it as a real bug that needs fixing or a just quirk of the language?