scope content dropdowns to the same universe, if present

app/views/content/form/_groupship_fields.html.erb

@@ -26,6 +26,7 @@
             f.select "#{attribute}_id",
               current_user.send("linkable_#{klass.pluralize}")
                 .in_universe(@universe_scope)
+                .in_universe(@content.universe)
                 .sort_by(&:name)
                 .reject { |content| content.class.name == klass && content.id == @content.id }
                 .map { |c| [c.name, c.id] }