The editor will pass UAT the -NoCompile flag when building a Blueprint only project, however UBT has been changed to throw an exception if it detects VS2012 as the only available compiler (UEBuildWindows.cs - WindowsPlatform::RegisterBuildPlatformInternal), and this exception is being thrown even when we're not actually going to compile (ScriptCompiler::FindAndCompileAllScripts calls RegisterAllUBTClasses, and probably needs to do something with its calculated DoCompile variable).
1) Set up a PC with VS2012 as the only installed version of VS.
2) Create a new Blueprint only project.
3) Package that project via the editor.
Head over to the existing Questions & Answers thread and let us know what's up.