This fixes some two-digit year rounding bugs that started triggering
because 2020 is closer to 2070 than 1970. Apparently two digits years
are still a thing.
highlight's Perl bindings are currently disabled on Darwin, but I
didn't make the dependency here conditional so that if that is ever
fixed, this function won't need to be updated. p-i is smart enough to
disable the test for highlight if it can't find the Perl module.
