Imported projitems with Content always fails dependency check

If you Import a shared project (projitems) which contains Content (set to PreserveNewest in this case) then msbuild always thinks the content files are missing in the output folder, even when they are present.

It seems that the dependency check thinks the content output should be in the wrong location. The actual Copy task does the right thing (i.e., copies the shared project content to the output folder of the project with the dependency).

I have verified this behaviour on a minimal C# UWP app created with Visual Studio 2017. See attached project - every time you hit "run" it will build. If you remove the csproj's dependency on the shared project, then successive runs will skip the build step.

[SharedContentTest.zip](https://github.com/Microsoft/msbuild/files/1271761/SharedContentTest.zip)