dbmigrate not compatible with SCL and bundler_ext
The installer currently calls extras/dbmigrate, but it tries to do a bundle exec without being aware that bundler_ext moves the Gemfile. It should check for Gemfile.in and skip the bundle exec if bundler_ext is in use.
It also calls rake directly rather than the SCL rake. It might be best to fix this during the package build, in a similar way to how foreman.spec updates the init.d script.