[perl #125122] [BUG] capturing to lexical variable buggy

[via RT]

# New Ticket Created by  Tobias Leich 
# Please include the string:  [perl #125122]
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# <URL: https://rt.perl.org/Ticket/Display.html?id=125122 >


Here it explodes:

my $foo; "abcd" ~~ m/a $foo=(..) d/
rakudo-moar 343474: OUTPUT«===SORRY!===␤QAST::Block with cuid 
cuid_1_1430941905.97113 has not appeared␤»

Here it makes the match fail:
my $foo; say "abcd" ~~ m/a  $foo=[..]  d/
rakudo-moar 343474: OUTPUT«False␤»

My guess is that it interpolates the variable instead of treating it as an 
alias to the capture.