punycode_decode not stateless

[vandepitte]

Version: 1.7.3

> urltools::puny_decode(c('xn--1qqw23a', 'xn--1ck2e1b', 'xn--1qqw23a'))
[1] "佛山"   "セール" "佛山ル"

First and third element in vector are the same, but are differently decoded because of second element in the vector. Note: both a-labels are valid (they are delegated TLDs by ICANN)