[perl #117235] [BUG] Deep-cloned array loses its original content on .unshift in Rakudo

[Carl Mäsak]

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<masak> just found my heisenbug :)
<masak> yeah, this is a weird one.
<diakopter> run it?
<masak> rn: my $c = [[1]].map({ [ @$_ ] }); $c.push( 42 ); say $c.perl
<p6eval> rakudo 9be4cc, niecza v24-35-g5c06e28: OUTPUT«([1], 42).list.item␤»
<masak> rn: my $c = [[1]].map({ [ @$_ ] }); $c.unshift( 42 ); say $c.perl
<p6eval> rakudo 9be4cc: OUTPUT«(42,).list.item␤»
<p6eval> ..niecza v24-35-g5c06e28: OUTPUT«(42, [1]).list.item␤»
* masak submits rakudobug
<masak> rn: my $c = [[1], [2], [3]].map({ [ @$_ ] }); $c.unshift( 42
); say $c.perl
<p6eval> niecza v24-35-g5c06e28: OUTPUT«(42, [1], [2], [3]).list.item␤»
<p6eval> ..rakudo 9be4cc: OUTPUT«(42,).list.item␤»

Niecza is right throughout, of course. The .unshift method adds
elements; it doesn't remove them.