Try to address flaky test

Author: lukebakken

projects/Unit/Fixtures.cs

@@ -519,6 +519,8 @@ public class TimingFixture
         public static readonly TimeSpan TimingInterval = TimeSpan.FromMilliseconds(300);
         public static readonly TimeSpan TimingInterval_2X = TimeSpan.FromMilliseconds(600);
         public static readonly TimeSpan TimingInterval_4X = TimeSpan.FromMilliseconds(1200);
+        public static readonly TimeSpan TimingInterval_8X = TimeSpan.FromMilliseconds(2400);
+        public static readonly TimeSpan TimingInterval_16X = TimeSpan.FromMilliseconds(4800);
         public static readonly TimeSpan SafetyMargin = TimeSpan.FromMilliseconds(150);
         public static readonly TimeSpan TestTimeout = TimeSpan.FromSeconds(5);
     }

projects/Unit/TestBlockingCell.cs

@@ -140,7 +140,7 @@ public void TestBackgroundUpdateSucceedsWithInfiniteTimeoutTimeSpan()
         public void TestBackgroundUpdateFails()
         {
             var k = new BlockingCell<int>();
-            SetAfter(TimingInterval_4X, k, 123);
+            SetAfter(TimingInterval_16X, k, 123);
 
             ResetTimer();
             Assert.Throws<TimeoutException>(() => k.WaitForValue(TimingInterval));