Without this diff, Blender will disregard the BLENDER_USER_SCRIPTS folder when preparing the Visual Studio solution. Normally, the Blender application will load scripts from the BLENDER_USER_SCRIPTS folder if it is defined, and this patch will make the Visual Studio project reference the same scripts that Blender would normally discover if this environment variable is defined. If BLENDER_USER_SCRIPTS is not defined, it will continue to behave as it did before and reference scripts in the user profile folder for the version of Blender being configured for building with Visual Studio.