This works now (probably for a while already) with rakudo. I added a test to S05-match/capturing-contexts.t with the following commit: https://github.com/perl6/roast/commit/5fe25b6de871608354e73b3e26cdd388d15e4e08
Please note that I test 'my $/ := 42' instead of '$/ := 42' (which also works for itself but which has unwanted effects on further tests).
