[Python-3000] Unicode IDs -- why NFC? Why allow ligatures?

["Martin v. Löwis"]

> The PEP assumes NFC, but I haven't really understood why, unless that
> is required for compatibility with other systems (in which case, it
> should be made explicit).

It's because UAX#31 tells us to use NFC, in section 5

"Generally if the programming language has case-sensitive identifiers,
then Normalization Form C is appropriate; whereas, if the programming
language has case-insensitive identifiers, then Normalization Form KC is
more appropriate."

As Python has case-sensitive identifiers, NFC is appropriate.

Regards,
Martin