I have created a branch on tfs2012 right next to the folder containing the main solution. Everything is identical. I also have a working TeamCity build configuration for the main solution. But when I clone the build configuration and change only the source file path in the build step, i get the following error:
The 'System.Net.NameResolution 4.0.0' package requires NuGet client version '2.12' or above, but the current NuGet version is '2.8.60717.93'.
NuGet's docs have a page dedicated to nuget.config, which has a large sample at the end.
For tooling support, if you have installed the .NET Core SDK, you can use dotnet new nugetconfig on the command line to create a file from a template. Tooling to modify this file isn't yet in the dotnet cli, so you'll need to download nuget.exe from nuget.org, then you can use commands like "nuget sources add" or "nuget config" to change values, just be sure to use the -ConfigFile paramater, as nuget.exe defaults to your user profile nuget.config, even when there's a nuget.config file in the current directory.
Ultimately it's just an XML file, so I feel like most people just edit it directly using samples online or the nuget.config reference I linked to as a guide.
