code contracts doesn't work with roslyn?

[scottcarr]

I enabled code contract checking in roslyn\Src\Compilers\Core\Portable\CodeAnalysis and I get:

C:\Users\carr27\Documents\GitHub\roslyn\src\Compilers\Core\Portable\CodeAnalysis.csproj(667,3): warning MSB4011: "C:
Users\carr27\Documents\GitHub\roslyn\src\Compilers\Core\Portable\Common.CodeContracts.props" cannot be imported again.
It was already imported at "C:\Users\carr27\Documents\GitHub\roslyn\src\Compilers\Core\Portable\CodeAnalysis.csproj (66
6,3)". This is most likely a build authoring error. This subsequent import will be ignored.

"C:\Users\carr27\Documents\GitHub\roslyn\src\RoslynLight.sln" (default target) (1) ->
"C:\Users\carr27\Documents\GitHub\roslyn\src\Compilers\Core\CodeAnalysisTest\CodeAnalysisTest.csproj" (default target)
(2) ->
"C:\Users\carr27\Documents\GitHub\roslyn\src\Test\Utilities\TestUtilities.csproj" (default target) (4) ->
"C:\Users\carr27\Documents\GitHub\roslyn\src\Compilers\Core\Desktop\CodeAnalysis.Desktop.csproj" (default target) (5) -

"C:\Users\carr27\Documents\GitHub\roslyn\src\Compilers\Core\Portable\CodeAnalysis.csproj" (default target) (6) ->
(CreateCodeContractReferenceAssembly target) ->
C:\Program Files (x86)\Microsoft\Contracts\MsBuild\v12.0\Microsoft.CodeContracts.targets(343,5): error MSB3073: The c
ommand ""C:\Program Files (x86)\Microsoft\Contracts\Bin\ccrefgen.exe" "@obj\Debug\CodeAnalysisccrefgen.rsp"" exited wit
h code 1. [C:\Users\carr27\Documents\GitHub\roslyn\src\Compilers\Core\Portable\CodeAnalysis.csproj]

1 Warning(s)
1 Error(s)