webapp: undefined method `load_all_models' for class `Class'

Exec[compile_assets] fails on canvasback (cdev webapp):

   - [canvasback] err: /Stage[main]/Site_webapp/Exec[compile_assets]/returns: change from notrun to 0 failed: /bin/bash -c "RAILS_ENV=production /usr/bin/bundle exec rake assets:precompile" returned 1 instead of one of [0] at /srv/leap/puppet/modules/site_webapp/manifests/init.pp:69

to debug using the cmd that puppet runs for Exec[compile_assets] shows this:

root@canvasback:/srv/leap/webapp# sudo -u leap-webapp /bin/bash -c "RAILS_ENV=production /usr/bin/bundle exec rake assets:precompile"
rake aborted!
undefined method `load_all_models' for class `Class'
/srv/leap/webapp/vendor/bundle/ruby/1.9.1/gems/activesupport-3.2.14/lib/active_support/core_ext/module/aliasing.rb:31:in `alias_method'
/srv/leap/webapp/vendor/bundle/ruby/1.9.1/gems/activesupport-3.2.14/lib/active_support/core_ext/module/aliasing.rb:31:in `alias_method_chain'
/srv/leap/webapp/core/lib/extensions/couchrest.rb:66:in `singletonclass'
/srv/leap/webapp/core/lib/extensions/couchrest.rb:65:in `'
/srv/leap/webapp/core/lib/extensions/couchrest.rb:45:in `'
/srv/leap/webapp/core/lib/extensions/couchrest.rb:2:in `'
/srv/leap/webapp/core/lib/extensions/couchrest.rb:1:in `'
/srv/leap/webapp/core/lib/leap_web_core.rb:10:in `require'
/srv/leap/webapp/core/lib/leap_web_core.rb:10:in `'
/srv/leap/webapp/config/application.rb:13:in `'
/srv/leap/webapp/Rakefile:13:in `require'
/srv/leap/webapp/Rakefile:13:in `'
(See full trace by running task with --trace)

(from redmine: created on 2013-10-09, closed on 2013-10-09, relates #4079 (closed), relates #4080 (closed), blocks #4077 (closed))