s3 := append(s2, s0...)            // append a slice              s3 is []int{0, 0, 2, 3, 5, 7, 0, 0}
s4 := append(s3[3:6], s3[2:]...)   // append overlapping slice    s4 is []int{3, 5, 7, 2, 3, 5, 7, 0, 0}

var t []interface{}
t = append(t, 42, 3.1415, "foo")   //                             t is []interface{}{42, 3.1415, "foo"}

var b []byte

If you used to rely on this behavior, now you should create the resources for background tasks inside the background task itself, and use internally only data that doesn't depend on the resources of dependencies with `yield`.