Importing was fixed to a good degree of confidence.
Sometimes the build give an error just from command line because of WPF related issues. The cause is that MSBuild have a different behavior on building solution compared with building from Visual Studio IDE. The fixes makes that nightly build to run (most likely) from first step. But if not, the errors may be solved using a similar pattern:
The error says like: cannot find 'Command' as property in base class. And the code is like: CustomControl subclasses (derives) a RibbonMappingControl which in itself inherits a RibbonButton. The CustomControl class should write RibbonMappingControl.Command instead of RibbonButton.Command.
So probably a nightly build will follow soon to test the blogs entries that are up-to-date and you may enjoy using those features.