UPDATE (solved fsvo)

/UPDATE

Greetings venerable monks,

While I think (humbly) I have a rather good grasp of how unicode is handled by perl in and out, I find myself stumped by the following example:

perl -e '
  my $str = { map { $_ => "\x{A9}" } qw(byte char) };
  utf8::upgrade($str->{char});
  for (keys %$str) {
    open (my $fh, "<", \do{$str->{$_}});
    printf( "$_ is read as %s\n", unpack "H*", <$fh>);
  }
  printf "Strings are: %s\n",
    ($str->{byte} eq $str->{char} ? "equal" : "different")
  ;
'
[download]

I understand why "char" and "byte" are considered equal. What I do not understand is why the internal storage details "leak" through the in-memory filehandle.

Explanations welcome!