Dash in Extension Names

Hackers,

So after Tom made "--" the separator between an extension name and the version information in extension file names --
becauseone might use "-" in the name itself, but probably not "--" -- it seems that the dash is not actually allowed: 
   create extension pgtap-core;   ERROR:  syntax error at or near "-"   LINE 1: create extension pgtap-core;

Parser error?

Thanks,

David