Fix bug in perform-genetic-operators
Fix bug in perform-genetic-operators

Because the assoc was only being performed when the child wasn't
oversized, and because revert-too-big-child doesn't always set the
:genetic-operator, it was previously possible to produce children with
no :genetic-operator.

thelmuth/Clojush,Vaguery/Clojush,saulshanabrook/Clojush,Vaguery/Clojush,saulshanabrook/Clojush,NicMcPhee/Clojush,lspector/Clojush,thelmuth/Clojush,lspector/Clojush,NicMcPhee/Clojush