[perl #130774] [BUG] Rational.REDUCE-ME has a data race

[Zoffix Znet via RT]

Data race is now fixed (in a post release branch):

Rakudo fix: 
https://github.com/rakudo/rakudo/commit/6dd20588b6dfb75a121e2207df5f8c89aad3e1ef
Test: https://github.com/perl6/roast/commit/1d10e9dc12