[perl #116348] [BUG] infix:<...> shouldn't autothread because of a junction in the RHS in Rakudo

[Christian Bartolomaeus via RT]

I added a test to S03-sequence/misc.t with the following commit: 
https://github.com/perl6/roast/commit/7f16f13f8c9610d57a6efb3eca0e846edbb6ed07