[perl #129812] [OPTIMIZER] `is rw` candidates get called even if a non-rw argument is passed

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# New Ticket Created by  Zoffix Znet 
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# <URL: https://rt.perl.org/Ticket/Display.html?id=129812 >



This code shows the bug:

     zoffix@leliana:~$ perl6 -e 'm: multi foo ($) {"right" }; multi  
foo ($ is rw) {"wrong"}; say foo "42"'
     wrong

And if we turn off the optimizer, we get the right candidate called  
(same would happen if we add more complex sub bodies, so possibly the  
sub gets inlined):

     zoffix@leliana:~$ perl6 --optimize=off -e 'm: multi foo ($)  
{"right" }; multi foo ($ is rw) {"wrong"}; say foo "42"'
     right