This look like a bogus test to me.
On the RHS of the ~~ operator, `$_` is bound to the LHS string "aaabccc".
`$var ??` evaluates the regex $var in boolean context, which causes it to match
against this string.
Since there is no match, this causes the ternary operator to return the
`rx{abc}` branch, which in turn matches at the current position in the outer
regex.
So unless I'm missing something, it is wrong for the test to expect no match
for the outer regex, and Rakudo already does the right thing.
What's the protocol for removing/changing tests in roast?
