IBM's definition of CP437[1] makes it clear that this character should
be a closed phi, but for some reason their mapping from Graphic
Character Global Identifier (GCGID) to Unicode gets the two phi
variants the wrong way around, which means that a lot of CP437 to
Unicode mappings list this character as U+03C6.
[1] <http://www-01.ibm.com/software/globalization/cp/cp00437.html>