idn2 fails with uppercase (german) umlauts

[Tim Ruehsen]

Hi,

could you give me a hint why
        idn2 ä
works (translates to xn--4ca), but
        idn2 Ä
results in 'lookup: string contains a disallowed character' ?

The 'old' idn works in both cases.

Is this by purpose (should I convert my utf-8 domains names to lowercase 
before calling libidn2 lookup functions) or will this behaviour be fixed ?
I just need a clarification...

I am on UTF-8 (en_US.UTF-8, Debian SID, libidn2-0:amd64 0.9-1).

Debug output:

        idn2 --debug ä
Charset: UTF-8
input[0] = 0xc3
input[1] = 0xa4
UCS-4 input[0] = U+00e4
output[0] = 0xc3
output[1] = 0xa4
UCS-4 output[0] = U+00e4
xn--4ca

        idn2 --debug Ä
Charset: UTF-8
input[0] = 0xc3
input[1] = 0x84
UCS-4 input[0] = U+00c4
idn2: lookup: string contains a disallowed character

Thanks and best regards,

      Tim Rühsen