System.Net.Http.Functional.Tests.HttpClientHandler_DangerousAcceptAllCertificatesValidator_Test.SetDelegate_ConnectionSucceeds failed with Cannot acquire the global certificate mutex.

[danmoseley]

https://ci.dot.net/job/dotnet_corefx/job/release_2.0.0/job/osx10.12_debug_prtest/84/testReport/junit/System.Net.Http.Functional.Tests/HttpClientHandler_DangerousAcceptAllCertificatesValidator_Test/SetDelegate_ConnectionSucceeds_acceptedProtocol__Tls__Tls11__Tls12__requestOnlyThisProtocol__False_/

System.Net.Http.Functional.Tests.HttpClientHandler_DangerousAcceptAllCertificatesValidator_Test.SetDelegate_ConnectionSucceeds(acceptedProtocol: Tls, requestOnlyThisProtocol: True) (from (empty))

Failing for the past 1 build (Since Aborted#84 )
Took 30 sec.
Stacktrace

MESSAGE:
Cannot acquire the global certificate mutex.\nExpected: True\nActual: False
+++++++++++++++++++
STACK TRACE:
at System.Net.Test.Common.Configuration.Certificates.GetCertificateCollection(String certificateFileName) in /Users/dotnet-bot/j/workspace/dotnet_corefx/release_2.0.0/osx10.12_debug_prtest/src/Common/tests/System/Net/Configuration.Certificates.cs:line 48 at System.Net.Test.Common.Configuration.Certificates.GetServerCertificateCollection() in /Users/dotnet-bot/j/workspace/dotnet_corefx/release_2.0.0/osx10.12_debug_prtest/src/Common/tests/System/Net/Configuration.Certificates.cs:line 34 at System.Net.Test.Common.Configuration.Certificates.GetServerCertificate() in /Users/dotnet-bot/j/workspace/dotnet_corefx/release_2.0.0/osx10.12_debug_prtest/src/Common/tests/System/Net/Configuration.Certificates.cs:line 24 at System.Net.Test.Common.LoopbackServer.<AcceptSocketAsync>d__9.MoveNext() in /Users/dotnet-bot/j/workspace/dotnet_corefx/release_2.0.0/osx10.12_debug_prtest/src/Common/tests/System/Net/Http/LoopbackServer.cs:line 107 --- 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.Net.Http.Functional.Tests.HttpClientHandler_DangerousAcceptAllCertificatesValidator_Test.<>c__DisplayClass1_0.<<SetDelegate_ConnectionSucceeds>b__0>d.MoveNext() in /Users/dotnet-bot/j/workspace/dotnet_corefx/release_2.0.0/osx10.12_debug_prtest/src/System.Net.Http/tests/FunctionalTests/HttpClientHandlerTest.AcceptAllCerts.cs:line 46 --- 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.Net.Test.Common.LoopbackServer.<>c__DisplayClass3_0.<CreateServerAsync>b__0(Task t) in /Users/dotnet-bot/j/workspace/dotnet_corefx/release_2.0.0/osx10.12_debug_prtest/src/Common/tests/System/Net/Http/LoopbackServer.cs:line 57 at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state) at System.Threading.Tasks.Task.ExecuteWithThreadLocal(Task& currentTaskSlot) --- 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.Net.Http.Functional.Tests.HttpClientHandler_DangerousAcceptAllCertificatesValidator_Test.<SetDelegate_ConnectionSucceeds>d__1.MoveNext() in /Users/dotnet-bot/j/workspace/dotnet_corefx/release_2.0.0/osx10.12_debug_prtest/src/System.Net.Http/tests/FunctionalTests/HttpClientHandlerTest.AcceptAllCerts.cs:line 44 --- 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)

[stephentoub]

This isn't specific to this test; it's the helper that's loading a cert blocking.
cc: @CIPop

[stephentoub]

Dup of https://github.com/dotnet/corefx/issues/19430 (different test, but same global mutex failure)