anchor.diff:      | _ -> 
           let deps =
               allReferences
  -            |> List.filter (fun (groupName, np, isReferencedProject) ->
  -                if isReferencedProject then true
  -                else
  +            |> List.filter (fun (group, np) ->
  +                match group with
  +                | None ->  true
  +                | Some groupName ->
                       try
                           // TODO: it would be nice if this data would be in the NuGet OData feed,
                           // then we would not need to parse every nuspec here
  
positive.code:                     let dep =
                          match dependencyVersionRequirement with
                          | Some installed -> installed
                          | None -> 
                              if isReferencedProject then
                                  match version with
                                  | Some v -> VersionRequirement.Parse (v.ToString())
                                  | None -> VersionRequirement.AllReleases
                              else 
                                  failwithf "No package with id '%A' installed in group %O." np.Name groupName
                      np.Name, dep)
          deps |> List.fold addDependency withDepsAndIncluded
  
negative.code:                             let settings : PackageInstallSettings = 
                                  { Name = PackageName name
                                    Settings = InstallSettings.Default }
                              yield None, settings
                      else
                          yield! getPackages proj
                  | None ->
  