common: Fix elements are doubling when append a not assignable type

Fixes #6188

common/collections/append.go

@@ -65,6 +65,7 @@ func Append(to interface{}, from ...interface{}) (interface{}, error) {
 		fv := reflect.ValueOf(f)
 		if !fv.Type().AssignableTo(tot) {
 			// Fall back to a []interface{} slice.
+			tov, _ := indirect(reflect.ValueOf(to))
 			return appendToInterfaceSlice(tov, from...)
 		}
 		tov = reflect.Append(tov, fv)