Strings in Python 3 are already unicode.

Looking at the patch, I see a lot of fractions which display as the missing glyph white square. For example, instead of seeing 1/9, which displays perfectly everywhere, I see a mysterious box similar to □.

Even when I see one, there's the visual inconsistency between fractions which display like ½ and those that display like ¹²/₄₅ which frankly just looks ugly to me. One problem is that in many fonts, the glyphs for superscript and subscript digits are a hodge-podge of sizes and styles with no consistent design.

If you're going to do this, you ought to use U+2044 FRACTION SLASH rather than U+002F SOLIDUS: compare ¹²⁄₄₅ with the above. If your font is decent, and many are not, the fraction slash is tighter and allows the numerator and denominator to overlap the slash, closer to the visual look of ½.

I would strongly oppose this becoming the default __str__ of fractions.