MSBuild doesn't produce project.json.lock file making the build fail.

* Open VS 2015 RTM

* Create Visual C#->Windows->Universal->Bank App(Universal Windows), for ex. name it BlankApp

* Delete project.json.lock file

* Try to execute:

set VisualStudioVersion=14.0
CD "%~dp0"
"C:\Program Files (x86)\MSBuild\14.0\Bin\MSBuild.exe" "BlankApp.sln" /p:Configuration="Debug" /p:Platform="x86"  /t:Rebuild 

you'll get errors like this:

"D:\Projects\Metro\BlankApp\BlankApp.sln" (Rebuild target) (1) ->
"D:\Projects\Metro\BlankApp\BlankApp\BlankApp.csproj" (Rebuild target) (2) ->
(MarkupCompilePass1 target) ->
  D:\Projects\Metro\BlankApp\BlankApp\BlankApp.csproj : XamlCompiler error WMC1006: Cannot resolve Assembly or Windows Metadata file 'System.Runtime.dll'
  C:\Program Files (x86)\MSBuild\Microsoft\WindowsXaml\v14.0\8.2\Microsoft.Windows.UI.Xaml.Common.targets(263,5): Xaml Internal Error error WMC9999: Type univ
erse cannot resolve assembly: System.Runtime, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a. [D:\Projects\Metro\BlankApp\BlankApp\BlankApp.csproj]

    0 Warning(s)
    2 Error(s)

The error would be gone if project.json.lock is available.

Now if you'll open the project with VS 2015 again, and hit build, VS will regenerate project.json.lock..

My question is, how can I force MSBuild to generate project.json.lock ?