perl6: .can does not recognize fallback code

fallback-issue.p6

# Apparently the .can method doesn't recognize what's done with
# fallback code.  Is that intended?

use v6;

class A { 

  INIT {
    $?PACKAGE.^add_fallback(
      # Only provide a fallback function for "foo"
      sub ($object, $name) { return ($name eq 'foo') ?? True !! False; },
      sub ($object, $name) { return method () {'A can .foo'} }
    );  
  }
}

my $a = A.new();

say $a.foo;
say $a.can('foo') ?? 'A can .foo' !! 'A cannot .foo';

# output:
#
#   A can .foo
#   A cannot .foo
#
# Is this an error?