[MS.Build] metadata is also replaced its windows path separators.
[MS.Build] disable failing test.

It somehow passes on my dev. environment so I cannot reproduce...
[msbuild] fix some weird local result variable initialization issue.

I cannot explain why, but this affects building solution that has more than
one projects for MS.Build.dll. <MSBuild/> task returns false for successful
builds without this change.
Most likely codegen or runtime issue, but a bit too high level to drill down.