Edit by @antonfirsov: recent failures seem to happen on Windows only, see #1479 (comment).

Test: System.Net.Sockets.Tests.SendReceiveMemoryNativeTask.SendRecvPollSync_TcpListener_Socket(listenAt: ::1, pollBeforeOperation: True) has failed.

MESSAGE:
Assert.Equal() Failure\nExpected: 123456\nActual: 123455
+++++++++++++++++++
STACK TRACE:
at System.Net.Sockets.Tests.SendReceive`1.SendRecvPollSync_TcpListener_Socket(IPAddress listenAt, Boolean pollBeforeOperation) in /mnt/j/workspace/dotnet_corefx/master/outerloop_netcoreapp_ubuntu16.04_debug/src/System.Net.Sockets/tests/FunctionalTests/SendReceive.cs:line 630 --- End of stack trace from previous location where exception was thrown ---

Details:
https://ci.dot.net/job/dotnet_corefx/job/master/job/outerloop_netcoreapp_ubuntu16.04_debug/403/testReport/System.Net.Sockets.Tests/SendReceiveMemoryNativeTask/SendRecvPollSync_TcpListener_Socket_listenAt____1__pollBeforeOperation__True_/