[perl #129271] [REGEX] Captures from interpolated variables do not capture

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# New Ticket Created by  Zoffix Znet 
# Please include the string:  [perl #129271]
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<Zoffix> m: my $m = 'a 123' ~~ /(\d\d\d)/; dd [$m.list];
<camelia> rakudo-moar 2c95f7: OUTPUT«[Match.new(ast => Any, list => (), hash => 
Map.new(()), orig => "a 123", to => 5, from => 2)]␤»
<Zoffix> m: my $input = '(\d\d\d)'; my $m = 'a 123' ~~ /<$input>/; dd [$m.list];
<camelia> rakudo-moar 2c95f7: OUTPUT«[]␤»


Expected results: output is the same, as the $input contains a capture that 
should capture stuff when interpolated.