std.regex: bug or something special?

[Lubos Pintes]

Hi,
I am reading std.regex. I found the following code on line 671:
         else if('A' <= current && current <= 'Z')
             val = val * 16 + current - 'A' + 10;

Hex digits are parsed there. So unles this is something special, this is 
a bug. Because for example what 'J' would mean in this context?