src/os: revert accidentally submitted change

Change-Id: Ib34984a6bd0abc76266e8aac96f9f8ad8ae21d17
Reviewed-on: https://go-review.googlesource.com/c/go/+/322894
Trust: Damien Neil <dneil@google.com>
Run-TryBot: Damien Neil <dneil@google.com>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

src/os/pipe_test.go

@@ -462,7 +462,7 @@ func TestFdReadRace(t *testing.T) {
 		// Give the other goroutine a chance to enter the Read.
 		// It doesn't matter if this occasionally fails, the test
 		// will still pass, it just won't test anything.
-		//time.Sleep(10 * time.Millisecond)
+		time.Sleep(10 * time.Millisecond)
 		r.Fd()
 
 		// The bug was that Fd would hang until Read timed out.