Version used: Visual Studio 2017 (15.2 (26430.6)) Release
Create projects as follows:

Sample Projects: NewCsproj.zip
Successfully compiled and show "BBBB".
Compilation error:
5>C:\Program Files\dotnet\sdk\2.0.0-preview1-005977\Sdks\Microsoft.NET.Sdk\build\Microsoft.NET.Sdk.targets(94,5): error : Cannot find project info for 'c:\users\***\documents\visual studio 2017\Projects\NewCsprojWeb\ClassLibraryA\ClassLibraryA.csproj'. This can indicate a missing project reference.
In your ClassLibraryDependingOnA, you can add PrivateAssets=All to the ProjectReference to ClassLibraryA like this:
<ItemGroup>
<ProjectReference Include="..\ClassLibraryA\ClassLibraryA.csproj" PrivateAssets="All" />
</ItemGroup>
This will stop the flow of ClassLibraryA further up the graph.
Most helpful comment
In your ClassLibraryDependingOnA, you can add PrivateAssets=All to the ProjectReference to ClassLibraryA like this:
This will stop the flow of ClassLibraryA further up the graph.