[perl #131925] Smartmatching a junction against a regex object vs m// (‘a’|‘b’ ~~ m/‘a’/)

[Sam S. via RT]

The problem only appears if `m//` is used directly as the RHS of `~~`:

    $_ = 'a' | 'b';
    say m/a/;           # any(｢a｣, Nil)
    say $_ ~~ m/a/;     # False
    say $_ ~~ { m/a/ }; # any(｢a｣, Nil)