TestReleaseThenReAcquireWithConcurrentAccess fails on CI

[davidjohnoliver]

I'm submitting a...

• Bug report (I searched for similar issues and did not find one)

Current behavior

Test fails with an error like the following:

Test method Uno.Core.Tests.Threading.AsyncLockFixture.TestReleaseThenReAcquireWithConcurrentAccess threw exception:
System.Exception: ****ANOTHER**** Test runner (TestReEntrencyWithConcurrentAccess@333) failed with: Safe handle has been closed

Stack trace
    at Uno.Threading.FastTaskCompletionSource`1.GetResult() in \src\Uno.Core\Threading\FastTaskCompletionSource.cs:line 283
   at Uno.Threading.FastTaskCompletionSource`1.<CreateAsyncTask>d__38.MoveNext() in \src\Uno.Core\Threading\FastTaskCompletionSource.cs:line 367
--- End of stack trace from previous location where exception was thrown ---
   at Uno.Threading.FastTaskCompletionSource`1.GetResult() in \src\Uno.Core\Threading\FastTaskCompletionSource.cs:line 283
   at Uno.Threading.FastTaskCompletionSource`1.<CreateAsyncTask>d__38.MoveNext() in \src\Uno.Core\Threading\FastTaskCompletionSource.cs:line 367
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Uno.Core.Tests.Threading.AsyncLockFixture.<TestReleaseThenReAcquireWithConcurrentAccess>d__14.MoveNext() in \src\Uno.Core.Tests\Threading\AsyncLockFixture.cs:line 415
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.VisualStudio.TestPlatform.MSTestAdapter.PlatformServices.ThreadOperations.ExecuteWithAbortSafety(Action action)

Expected behavior

Test passes

Minimal reproduction of the problem with instructions

Un-ignore the test and run on the CI. (Locally it seems ok.)

Environment

Nuget Package: 

Package Version(s): 

Affected platform(s):
- [ ] iOS
- [ ] Android
- [ ] WebAssembly
- [ ] Windows
- [ ] Build tasks

Visual Studio
- [ ] 2017 (version: )
- [ ] 2017 Preview (version: )
- [ ] for Mac (version: )

Relevant plugins
- [ ] Resharper (version: )