Getting Rid of Gomobile in plone
some more deleting of gomobile - read other pages to find stuff in the zope-configuration interface
I used wildcard.fix-perisitent-utilities. Wenn started for the site root it crashed with a type error in line 185 (get set descriptor as argument for encodeb64). It could be started from the plone root and I manually requested to remove the gomobile interface class (the one that shows up in the error message when trying to modify extensions). Then it could be started from the site root and actually re-added that class (and some more) as a fake class.
Now suddenly everything works normal (I hope it stays that way).