roslyn: cannot build latest master

I get this error:

1>------ Build started: Project: Microsoft.CodeAnalysis, Configuration: Debug Any CPU ------
1>C:\Program Files\dotnet\sdk\3.0.100-preview6-012264\Sdks\Microsoft.NET.Sdk\targets\Microsoft.PackageDependencyResolution.targets(257,7): error MSB4064: The "DesignTimeBuild" parameter is not supported by the "ResolvePackageAssets" task. Verify the parameter exists on the task, and it is a settable public instance property.
1>C:\Program Files\dotnet\sdk\3.0.100-preview6-012264\Sdks\Microsoft.NET.Sdk\targets\Microsoft.PackageDependencyResolution.targets(234,5): error MSB4063: The "ResolvePackageAssets" task could not be initialized with its input parameters.
1>Done building project "Microsoft.CodeAnalysis.csproj" -- FAILED.
2>------ Build started: Project: Microsoft.CodeAnalysis.Workspaces, Configuration: Debug Any CPU ------
2>C:\Program Files\dotnet\sdk\3.0.100-preview6-012264\Sdks\Microsoft.NET.Sdk\targets\Microsoft.PackageDependencyResolution.targets(257,7): error MSB4064: The "DesignTimeBuild" parameter is not supported by the "ResolvePackageAssets" task. Verify the parameter exists on the task, and it is a settable public instance property.
2>C:\Program Files\dotnet\sdk\3.0.100-preview6-012264\Sdks\Microsoft.NET.Sdk\targets\Microsoft.PackageDependencyResolution.targets(234,5): error MSB4063: The "ResolvePackageAssets" task could not be initialized with its input parameters.
2>Done building project "Microsoft.CodeAnalysis.Workspaces.csproj" -- FAILED.

I have cleaned and restored. I am on: