Fix handling of TimeoutError in io_wait.

lib/async/scheduler.rb

@@ -171,17 +171,11 @@ def io_wait(io, events, timeout = nil)
 
 			if timeout
 				timer = @timers.after(timeout) do
-					fiber.raise(TimeoutError)
+					fiber.transfer
 				end
 			end
 
-			# Console.logger.info(self, "-> io_wait", fiber, io, events)
-			events = @selector.io_wait(fiber, io, events)
-			# Console.logger.info(self, "<- io_wait", fiber, io, events)
-
-			return events
-		rescue TimeoutError
-			return false
+			return @selector.io_wait(fiber, io, events)
 		ensure
 			timer&.cancel
 		end

test/async/task.rb

@@ -596,12 +596,14 @@ def after
 			expect(state).to be == :timeout
 		end
 
-		it "will timeout while getting from stdin" do
+		it "will timeout while getting from input" do
+			input, output = IO.pipe
 			error = nil
 
 			reactor.async do |task|
 				begin
-					task.with_timeout(0.1) {STDIN.gets}
+					# This can invoke `io_wait`, which previously had `rescue TimeoutError`, causing the timeout to be ignored.
+					task.with_timeout(0.1) {input.gets}
 				rescue Async::TimeoutError => error
 				  # Ignore.
 				end
@@ -610,6 +612,9 @@ def after
 			reactor.run
 
 			expect(error).to be_a(Async::TimeoutError)
+		ensure
+			input.close
+			output.close
 		end
 
 		it "won't timeout if execution completes in time" do