Warning_Could not resolve this reference. Could not locate the assembly

Hi,

I am killing the building warnings of project under vs2015 CTP5.

There is one warning which shows that The referenced component 'Microsoft.VisualStudio.Shell.12.0' could not be found.

So I delete the object in References and the warning disappear. Then I rebuild the project.

But one new warning appear and shows:

Could not resolve this reference. Could not locate the assembly "Microsoft.VisualStudio.Shell.12.0, Version=12.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL". Check to make sure the assembly exists on disk. If this reference is required by your code, you may get compilation errors.

It's very weird. Since I have removed the reference, the vs should not go to search the Microsoft.VisualStudio.Shell.12.0.

Is it a bug of CTP5?

Or any dll depends on Microsoft.VisualStudio.Shell.12.0? which result vs to search that dll.