lvalue subroutine behaviour changes

gistfile1.pl

# In days of yore, this would print ONCE UPON A TIME.
# In bleadperl, it prints BUT NOWADAYS
#
# Can anyone point me to what has changed?

use strict; use feature 'say';
my $x = "ONCE UPON A TIME";
sub foo :lvalue { $x; }

my $r = \(scalar foo());
$$r = "BUT NOWADAYS";
say $x;