Hello
At first. Installing anything from test is not supported and will never be. So better be patient and wait for release.
And now to your problem. You are installing new version of updater, but using old wrapper script. This means that, as you are warned, locally installed packages are not yet supported. So updater doesn’t know about this locally installed package and as first it updates you back to known version. That’s why I explicitly stated that you must reinstall locally installed packages after updater update. Which means for you install it twice.
To make sure that it isn’t seen as bug, let me explain here primary difference between Updater and standard package managers like opkg or apt and so on. Those are expected to be run by user and when they are not sure they ask him. Normally it means that they print error message and fail. User it self is required to fix it. This can happen even if you are not installing any new software, just during updates. This is specially prevalent for rolling release distributions. Because updater runs in background on device that is not probably often maintained and is expected to run years long without reinstall it has to be more hands off and robust than standard packages managers. This comes in cost of some limiting features that should ensure that updater will be able to update system even without user attention. Locally installed packages can break this and that is why their support is kind of limited and wasn’t implemented at first (although planned). And that is why repositories are preferred solution, because there is expectation that those will be updated, but local package can’t be updated and it might even freeze system components on some old version if you specify unfortunate dependencies.