The sources add command does not add the package source into the nuget config if the nuget.config doesn’t already have both a element and an existing package source. The command output of sources add is "package sources added successfully", while there is no package source added at all.

How to repo:

1. Change the nuget.config to only including following
   <?xml version="1.0" encoding="utf-8"?> <configuration />
2. Run nuget.exe Sources add -name {sourceName} -source {source}
   3.The output is "Package Source with Name: {sourceName} added successfully."
   4.Check nuget.config, no source has been added at all.

This bug is that nuget.exe fails to add the package source, while claims it added successfully.