On Rails 4.2, a railtie is getting added that has no name. This causes our initialiser that checks for deprecated engine initialisers to fail on Rails startup with the following error:

/home/dcleal/.rvm/gems/ruby-2.0.0-p353@foreman/gems/railties-4.2.5.1/lib/rails/railtie.rb:187:in `generate_railtie_name': undefined method `tr' for nil:NilClass (NoMethodError)
        from /home/dcleal/.rvm/gems/ruby-2.0.0-p353@foreman/gems/railties-4.2.5.1/lib/rails/railtie.rb:165:in `railtie_name'
        from /home/dcleal/.rvm/gems/ruby-2.0.0-p353@foreman/gems/railties-4.2.5.1/lib/rails/railtie.rb:201:in `railtie_name'
        from /home/dcleal/code/foreman/foreman/config/initializers/assets_paths.rb:9:in `block in <top (required)>'
        from /home/dcleal/.rvm/gems/ruby-2.0.0-p353@foreman/gems/railties-4.2.5.1/lib/rails/engine/railties.rb:13:in `each'
        from /home/dcleal/.rvm/gems/ruby-2.0.0-p353@foreman/gems/railties-4.2.5.1/lib/rails/engine/railties.rb:13:in `each'
        from /home/dcleal/code/foreman/foreman/config/initializers/assets_paths.rb:9:in `select'
        from /home/dcleal/code/foreman/foreman/config/initializers/assets_paths.rb:9:in `<top (required)>'

Debug shows:

> Rails.application.railties.find { |e| e.class.name.nil? }.inspect
#<#<Class:0x00000002f84f88>:0x00000005c678e8 @initializers=[]>

Handling of this can be backported safely to develop.