you are correct, but there should be something strange going on under the hood. it seems only Windows allows the bless \pop, shift trick.

This is perl, v5.8.0 built for MSWin32-x86-multi-thread -> ok
This is perl, v5.8.2 built for cygwin-thread-multi-64int -> ok
This is perl, v5.8.0 built for i686-linux -> dies

sorry for not checking this beforehand. however, the reason why it works on a platform and fails on another is beyond the scope of this thread :-)