XUnit build failures in 'prodcon/clicommandlineparser/release/2.1.3xx/' - '20180530.01'

There were a set of failures during this build. Here is a summary of these:

• https://devdiv.visualstudio.com/DefaultCollection/DevDiv/_build?_a=summary&buildId=1730386
  • Agent: DDMBLDW137
  • Error log: XUnit : error : E:\A_work\0\s\artifacts\platform\TestResults\Microsoft.DotNet.Cli.CommandLine.Tests_netcoreapp2.0_x64.log [netcoreapp2.0|x64] [E:\A_work\0\s\src\tests\CommandLine.Tests\Microsoft.DotNet.Cli.CommandLine.Tests.cspr...

@mmitche, @livarcocc