Enable passing BuildManager_Tests on .NET Core (#2013)
Enable passing BuildManager_Tests on .NET Core (#2013)

Progress toward #670.
rainersigwald/msbuild,rainersigwald/msbuild,jeffkl/msbuild,Microsoft/msbuild,mono/msbuild,jeffkl/msbuild,mono/msbuild,rainersigwald/msbuild,chipitsine/msbuild,Microsoft/msbuild,cdmihai/msbuild,rainersigwald/msbuild,sean-gilliam/msbuild,jeffkl/msbuild,AndyGerlicher/msbuild,mono/msbuild,chipitsine/msbuild,mono/msbuild,Microsoft/msbuild,sean-gilliam/msbuild,cdmihai/msbuild,AndyGerlicher/msbuild,Microsoft/msbuild,AndyGerlicher/msbuild,jeffkl/msbuild,sean-gilliam/msbuild,cdmihai/msbuild,chipitsine/msbuild,sean-gilliam/msbuild,AndyGerlicher/msbuild,cdmihai/msbuild,chipitsine/msbuild