Coverlet hangs when using System.Net.HttpStatusCode as a default parameter.

When running ```dotnet test``` from the command line with a project that uses ```System.Net.HttpStatusCode``` as a default parameter, the test hangs using one full CPU core.

I've traced this issue to Mono.Cecil, and when I update to 0.10.1, the issue goes away.

I'll attach an example that shows the problem.