bug#36887: coreutils-8.31: printf chokes on \u0041

[Ulrich Mueller]

>>>>> On Fri, 02 Aug 2019, Paul Eggert wrote:

> It's not entirely arbitrary. Because of the restriction, coreutils
> printf doesn't have to worry about what this command should do:

>   printf '\u0025d\n' 1 2

Seems quite obvious, it should do the same as these commands:

  printf '\045d\n' 1 2
  printf '\x25d\n' 1 2

This is different from C behaviour, because printf(3) doesn't deal with
backslash escapes at all, which are interpreted earlier during parsing
of the string literal. That's why I think the C reasoning doesn't apply
here.