runtime: System.Net.Tests.HttpRequestStreamTests.Read_FullLengthSynchronous_Success failed in CI

This test has a ~1% failure rate on windows 2008 when running on an offline CI machine repeatedly in a loop, and has recently failed in CI.

In all cases the detail is as follows (including the test arguments of True, “”)

   System.Net.Tests.HttpRequestStreamTests.Read_FullLengthSynchronous_Success(transferEncodingChunked: True, text: \"\") [FAIL]
      System.Net.Http.HttpRequestException : An error occurred while sending the request.
      ---- System.Net.Http.WinHttpException : The server returned an invalid or unrecognized response
      Stack Trace:
            at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
            at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
            at System.Runtime.CompilerServices.ConfiguredTaskAwaitable`1.ConfiguredTaskAwaiter.GetResult()
            at System.Net.Http.HttpClient.<FinishSendAsyncBuffered>d__58.MoveNext()
         --- End of stack trace from previous location where exception was thrown ---
            at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
            at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
            at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult()
            at System.Net.Tests.HttpRequestStreamTests.<Read_FullLengthSynchronous_Success>d__6.MoveNext()
         --- End of stack trace from previous location where exception was thrown ---
            at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
            at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
         --- End of stack trace from previous location where exception was thrown ---
            at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
            at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
         --- End of stack trace from previous location where exception was thrown ---
            at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
            at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
         ----- Inner Stack Trace -----
            at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
            at System.Threading.Tasks.RendezvousAwaitable`1.GetResult()
            at System.Net.Http.WinHttpHandler.<StartRequest>d__105.MoveNext()