Comment # 1 on bug 999735 from Michael Schr�der

Sorry, this was fixed with a couple of very big commits building on top of each
other. I don't see how I can backport those without risking other breakage.

Here's an easy reproducer, btw:

my $y = "f\N{U+00F6}bar\n";
my $x = "bar\n";
print "$-[0]\n" if $y =~ /$x/;
utf8::upgrade($x);
print "$-[0]\n" if $y =~ /$x/;

As for the update, this is not possible. It would mean that all other modules
need to be upgraded as well. While we could do that for our packages, 3rd party
stuff would break.