Please report this as a bug using the perlbug command. The documentation and behaviour don't match, and therefore one or both needs to be fixed.

Based upon a glance over the code, I'd say that it's Perl that needs fixing; if this behaviour of the ternary operator is documented, and it works some of the time, then it's probably perl that needs fixing, with a note in the documentation that the ?: operator may fall down with more complex expressions.