Investigate why CI fails often with TestCaptureOutput on

[nguerrera]

We started getting failures like this all of the sudden very often in CI (no repro locally):

F:\vsagent\10\s\.nuget\packages\microsoft.dotnet.arcade.sdk\1.0.0-beta.19065.6\tools\XUnit\XUnit.targets(93,5): error MSB3491: Could not write lines to file "F:\vsagent\10\s\artifacts\log\Release\Microsoft.DotNet.Configurer.UnitTests_netcoreapp3.0_x64.log". The process cannot access the file 'F:\vsagent\10\s\artifacts\log\Release\Microsoft.DotNet.Configurer.UnitTests_netcoreapp3.0_x64.log' because it is being used by another process. [F:\vsagent\10\s\test\Microsoft.DotNet.Configurer.UnitTests\Microsoft.DotNet.Configurer.UnitTests.csproj]

This is in a step in arcade where it appends to the log file that would have been written by a prior Exec with > redirected output to it. Somehow the file is still in use. Maybe exec returned before the handle was released? But how?

[github-actions]

Due to lack of recent activity, this issue has been labeled as 'stale'. It will be closed if no further activity occurs within 30 more days. Any new comment will remove the label.