$ perl -le'
    $_ = "<?xml version=\"1.0\"?><root>\x{C9}ric</root>";
    utf8::encode($_);
    utf8::downgrade($_);
    print length;
    print do { use bytes; length };
'
39
39

##</code><code>##

$ perl -le'
    $_ = "<?xml version=\"1.0\"?><root>\x{C9}ric</root>";
    utf8::encode($_);
    utf8::upgrade($_);
    print length;
    print do { use bytes; length };
'
39
41   XXX Should be 39

##</code><code>##

$ perl -le'
    $_ = "<?xml version=\"1.0\"?><root>\x{C9}ric</root>";
    print do { use bytes; length };
'
38   XXX Should be 39