.NET Standard and Visual Studio 2017 - visual-studio-2017

Question

I've installed recently released Visual Studio 2017 and created a .NET Standard Class Library project.
The .cproj just targets .NET Standard v1.4:
<Project Sdk="Microsoft.NET.Sdk">
<PropertyGroup>
<TargetFramework>netstandard1.4</TargetFramework>
</PropertyGroup>
</Project>
Within Visual Studio, it states that it successfully referenced the NETStandard.Library metapackage.
Within this library project, I have a simple class that utilizes System.Threading.Tasks.Task type.
using System;
using System.Threading.Tasks;
namespace ClassLibrary1
{
public class Class1
{
public Class1(Action action)
{
var task1 = Task.Run(action);
}
}
}
During the build in Visual Studio it does check compatibility with .NETStandard 1.4 against the dll-s found in nuget packages, however those dll-s are not copied to the output folder.
Checking compatibility for System.Threading 4.3.0 with
.NETStandard,Version=v1.4.
1> System.Threading.Tasks/4.3.0 1>
Name=System.Threading.Tasks 1>
Path=system.threading.tasks/4.3.0 1>
ResolvedPath=C:\Users\user-name\.nuget\packages\system.threading.tasks\4.3.0
1> Type=package 1> Version=4.3.0
The project compiles and produces dll (ClassLibrary1.dll) referencing only 2 assemblies: System.Runtime.dll and System.Threading.Tasks.dll.
Which are resolved to GAC dlls:
C:\Windows\Microsoft.NET\Framework\v4.0.30319\System.Runtime.dll
C:\Windows\Microsoft.NET\Framework\v4.0.30319\System.Threading.Tasks.dll
These are the Full .NET Framework 4.6.1586.0 assemblies, installed globally in my Windows and registered in GAC.
QUESTION: Is this a correct behavior? After reading the .NET Standard docs I was convinced that ClassLibrary1.dll would reference netstandard.dll which would act as a facade for nuget versions of System.Runtime.dll and System.Threading.Tasks.dll. And/or those dll-s would be copied into output directory along with ClassLibrary1.dll.