[perl #64478] Pairs constructor :pair and :!pair do not work properly in Rakudo

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# New Ticket Created by  Ilya Belikin 
# Please include the string:  [perl #64478]
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# <URL: http://rt.perl.org/rt3/Ticket/Display.html?id=64478 >


Ho there,

Pairs constructor changed:

S02, L2538

    Fat arrow           Adverbial pair  Paren form
    =========           ==============  ==========
    a => True           :a
    a => False          :!a


but in Rakudo, now:
> :a.perl.say
"a" => 1

> :!a.perl.say
"a" => 0

I hope this one easy to fix. Thank you!

Ilya