1.9 upper-case for constants?

I’m posting this here for some advice on whether this is a bug, or
intentional behaviour.

ruby 1.9.2-preview1 is quite capable of distinguishing Unicode
upper-case characters. However this doesn’t seem to be used when
deciding whether an identifier is a constant or a local variable.

SCHÖN = 1 # constant
=> 1

ÃœBER = 2 # local variable!
=> 2

=> [:SCHÖN]

=> [:ÃœBER]

I am not sure from the source code whether this is intentional or not.
In parse.c it uses rb_enc_isupper which understands encodings:

    else if (rb_enc_isupper(m[0], enc)) {
        id = ID_CONST;
    else {
        id = ID_LOCAL;

This is in rb_intern3. And yet it is called from rb_intern2 which says:

rb_intern2(const char *name, long len)
return rb_intern3(name, len, rb_usascii_encoding());

thereby ignoring the source encoding and saying always use ASCII rules.

Can someone confirm if this is the behaviour which is intended?