[Bug Report] ASP.NET add reference to PCL

Hello, I'm experimenting with porting our site to ASP.NET 5.  It took me a long time, but I finally figured out the "wrap" function to add references to our existing libraries.

However, I ran into some difficulty later on.  The references worked on my computer, but when I checked in all my files and tried to build from one of our build machines, it no longer loaded four of the six project reference.  The error message is below (same for all four).

ErrorNU1002The dependency MyApp.DataModel 1.0.0 in project MyApp.Hub.Net does not support framework DNX,Version=v4.5.1.

All four of those projects are Portable Class Libraries.  The other two are regular .NET class libraries.  I opened the wrap project.json and under the frameworks changed the name from either "net45+sl50+win" or "net40+sl50+win" to "net45", and that fixed it.  No modification was made to the projects or libraries themselves.

This seems like a bug, but I could be missing some important detail.  Any guidance would be welcome.

project.json

{"version": "1.0.0-*","frameworks": {"net45": {"wrappedProject": "../../../MyApp.DataModel/MyApp.DataModel.csproj","bin": {"assembly": "../../../MyApp.DataModel/obj/{configuration}/MyApp.DataModel.dll","pdb": "../../../MyApp.DataModel/obj/{configuration}/MyApp.DataModel.pdb"
      }
    }
  }
}