Msbuild seems to not exactly rebuild the unique solution like what VS does.

### Steps to reproduce

1. In VS2017, create a Class Library called Library1 (C# .net framework 4.0)
2. Use Packages.config format to consume a nuget package **microsoft.bcl.async** 1.0.168 version
3. In default Class1.cs file I have content:
```c#
public class Class1
{
static void TestMethod1()
{
Console.WriteLine("Have a nice day");
}
}
```

4.Then I create a new empty web site(C# .net framework 4.0), right-click the web-site to add reference to Library1, now right-click the solution=>rebuild the solution everything works well.

The Library rebuilds successfully, and the website successfully copy the latest Library1.dll to bin folder and PreCompile folder.

5.Now if I add some async methods into the Library1. The rebuild in VS works well with no warnings. code:

```C#
public class Class1
{
static void TestMethod1()
{
Console.WriteLine("Have a nice day");
}
static async Task F() => await TaskEx.Delay(100);
static void TestMethod2() => F().Wait();
}
```

### Expected behavior
Since the rebuilding solution in VS works well, now I want the msbuild command-line also works so that I can automate managing it.

### Actual behavior
However if now I use msbuild command-line, open developer command prompt for VS2017 and navigate to solution folder(cd path), use command: **msbuild xxx.sln /t:rebuild** it throw warnings like:
```
(Rebuild target) ->
C:\Users\xxx\source\repos\Library\WebSite1_1_.metaproj : warning MSB3268: The primary reference "C:\Users\lancel\s
ource\repos\Library\Library\bin\Debug\Library.dll" could not be resolved because it has an indirect dependency on the f
ramework assembly "System.Runtime, Version=1.5.11.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" which could not
be resolved in the currently targeted framework. ".NETFramework,Version=v4.0". To resolve this problem, either remove t
he reference "C:\Users\xxxx\source\repos\Library\Library\bin\Debug\Library.dll" or retarget your application to a fra
mework version which contains "System.Runtime, Version=1.5.11.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a".
```

And exactly the Library1.dll is not the latest one. Simple code in Library1.dll and the msbuild command-line works well and website will copy the latest Library1.dll. Async code in library1's class1.cs, and then the msbuild command-line won't work as I expected.

What confused me:

As it always works well when building in VS, so actually I try to make it still work in msbuild command-line, but I failed to do that. It only works when I use devenv.exe instead of msbuild.exe. Any hint would be appreciated!