 		set(d) {
 			_state.modify {
 				var s = $0
-				if s.innerDisposable === d {
-					return s
-				}
 
 				s.innerDisposable?.dispose()
 				s.innerDisposable = d


	/// Initializes the receiver to dispose of the argument when the
	/// SerialDisposable is disposed.
	convenience init(_ disposable: Disposable) {
		self.init()
		innerDisposable = disposable
	}



/// A disposable that only flips `disposed` upon disposal, and performs no other
/// work.
struct SimpleDisposable: Disposable {
	var _disposed = Atomic(false)

	var disposed: Bool {
