Personally, if I wanted to undef something and I was afraid it wouldn't be clear, I'd just use a comment...

 # Temporarily undef the INT signal handler
 local $SIG{INT};
[download]

or such. But depending on who else is working on the code or the background, I do think that

undef local $foo

can be clearer sans comment.

What I really took issue with is what I perceived as your tone towards the poster. There's been a bit of what I consider, undue rudness at the Monestary as of late. Electronic communication mediums are not always the best for deriving the "intonation" of a message and perhaps I misread the tone of your comment. Regardless, I don't think the example was a wrong answer just a differently right one.

-Lee

"To be civilized is to deny one's nature."