mergeDeep behavior inconsistent across different versions #1574
Description
I am getting inconsistent results for mergeDeep.
I am using version 4.0.0-rc.9
let obj1 = Immutable.fromJS({ x: [{ a: 1 }] });
let obj2 = Immutable.fromJS({ x: [{ b: 1 }] });
let result = obj1.mergeDeep(obj2);
// expected result { x: [{ a: 1, b: 1 }] }
// produced result { x: [{ a: 1 }, { b: 1 }] }if i downgrade to verison 3.8.2 it seems to behave correctly. Has the desired behavior changed or is there some kind of bug with version 4.0.0-rc.9?