Using a string as split's first argument is confusing if it's not a single whitespace (\x20). It'll still be interpreted as a regex, which is not what one would expect.
Simplifying split might make it into perl6, but we'll have to live with its current rules for now. Read RFC 361, the most important statement (imho) is: "Yes, split '.', $foo doesn't split on dot -- it's currently the same an split /./, $foo.)".

2;0 juerd@ouranos:~$ perl -e'undef christmas'
Segmentation fault
2;139 juerd@ouranos:~$
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