Assets precompile fails in production after enabling unicorn

deploy_error.txt

 Running: rake assets:precompile
       rake aborted!
       undefined method `match' for nil:NilClass
       /tmp/build_pz2syblot4iq/vendor/bundle/ruby/1.9.1/gems/mongoid-3.0.23/lib/mongoid/sessions/mongo_uri.rb:49:in `initialize'
       /tmp/build_pz2syblot4iq/vendor/bundle/ruby/1.9.1/gems/mongoid-3.0.23/lib/mongoid/sessions/factory.rb:103:in `new'
       /tmp/build_pz2syblot4iq/vendor/bundle/ruby/1.9.1/gems/mongoid-3.0.23/lib/mongoid/sessions/factory.rb:103:in `parse'
       /tmp/build_pz2syblot4iq/vendor/bundle/ruby/1.9.1/gems/mongoid-3.0.23/lib/mongoid/sessions/factory.rb:62:in `create_session'
       /tmp/build_pz2syblot4iq/vendor/bundle/ruby/1.9.1/gems/mongoid-3.0.23/lib/mongoid/sessions/factory.rb:43:in `default'
       /tmp/build_pz2syblot4iq/vendor/bundle/ruby/1.9.1/gems/mongoid-3.0.23/lib/mongoid/sessions.rb:109:in `default'
       /tmp/build_pz2syblot4iq/vendor/bundle/ruby/1.9.1/gems/mongoid-3.0.23/lib/mongoid.rb:124:in `default_session'
       /tmp/build_pz2syblot4iq/vendor/bundle/ruby/1.9.1/gems/mongoid-3.0.23/lib/mongoid/railtie.rb:142:in `block (2 levels) in <class:Railtie>'
       /tmp/build_pz2syblot4iq/vendor/bundle/ruby/1.9.1/gems/activesupport-3.2.9/lib/active_support/lazy_load_hooks.rb:34:in `call'
       /tmp/build_pz2syblot4iq/vendor/bundle/ruby/1.9.1/gems/activesupport-3.2.9/lib/active_support/lazy_load_hooks.rb:34:in `execute_hook'
       /tmp/build_pz2syblot4iq/vendor/bundle/ruby/1.9.1/gems/activesupport-3.2.9/lib/active_support/lazy_load_hooks.rb:43:in `block in run_load_hooks'
       /tmp/build_pz2syblot4iq/vendor/bundle/ruby/1.9.1/gems/activesupport-3.2.9/lib/active_support/lazy_load_hooks.rb:42:in `each'
       /tmp/build_pz2syblot4iq/vendor/bundle/ruby/1.9.1/gems/activesupport-3.2.9/lib/active_support/lazy_load_hooks.rb:42:in `run_load_hooks'
       /tmp/build_pz2syblot4iq/vendor/bundle/ruby/1.9.1/gems/railties-3.2.9/lib/rails/application/finisher.rb:59:in `block in <module:Finisher>'
       /tmp/build_pz2syblot4iq/vendor/bundle/ruby/1.9.1/gems/railties-3.2.9/lib/rails/initializable.rb:30:in `instance_exec'
       /tmp/build_pz2syblot4iq/vendor/bundle/ruby/1.9.1/gems/railties-3.2.9/lib/rails/initializable.rb:30:in `run'
       /tmp/build_pz2syblot4iq/vendor/bundle/ruby/1.9.1/gems/railties-3.2.9/lib/rails/initializable.rb:55:in `block in run_initializers'
       /tmp/build_pz2syblot4iq/vendor/bundle/ruby/1.9.1/gems/railties-3.2.9/lib/rails/initializable.rb:54:in `each'
       /tmp/build_pz2syblot4iq/vendor/bundle/ruby/1.9.1/gems/railties-3.2.9/lib/rails/initializable.rb:54:in `run_initializers'
       /tmp/build_pz2syblot4iq/vendor/bundle/ruby/1.9.1/gems/railties-3.2.9/lib/rails/application.rb:136:in `initialize!'
       /tmp/build_pz2syblot4iq/vendor/bundle/ruby/1.9.1/gems/railties-3.2.9/lib/rails/railtie/configurable.rb:30:in `method_missing'
       /tmp/build_pz2syblot4iq/config/environment.rb:5:in `<top (required)>'
       /tmp/build_pz2syblot4iq/vendor/bundle/ruby/1.9.1/gems/activesupport-3.2.9/lib/active_support/dependencies.rb:251:in `require'
       /tmp/build_pz2syblot4iq/vendor/bundle/ruby/1.9.1/gems/activesupport-3.2.9/lib/active_support/dependencies.rb:251:in `block in require'
       /tmp/build_pz2syblot4iq/vendor/bundle/ruby/1.9.1/gems/activesupport-3.2.9/lib/active_support/dependencies.rb:236:in `load_dependency'
       /tmp/build_pz2syblot4iq/vendor/bundle/ruby/1.9.1/gems/activesupport-3.2.9/lib/active_support/dependencies.rb:251:in `require'
       /tmp/build_pz2syblot4iq/vendor/bundle/ruby/1.9.1/gems/railties-3.2.9/lib/rails/application.rb:103:in `require_environment!'
       /tmp/build_pz2syblot4iq/vendor/bundle/ruby/1.9.1/gems/railties-3.2.9/lib/rails/application.rb:297:in `block (2 levels) in initialize_tasks'
       /tmp/build_pz2syblot4iq/vendor/bundle/ruby/1.9.1/gems/actionpack-3.2.9/lib/sprockets/assets.rake:93:in `block (2 levels) in <top (required)>'
       /tmp/build_pz2syblot4iq/vendor/bundle/ruby/1.9.1/gems/actionpack-3.2.9/lib/sprockets/assets.rake:60:in `block (3 levels) in <top (required)>'
       /tmp/build_pz2syblot4iq/vendor/bundle/ruby/1.9.1/gems/actionpack-3.2.9/lib/sprockets/assets.rake:23:in `invoke_or_reboot_rake_task'
       /tmp/build_pz2syblot4iq/vendor/bundle/ruby/1.9.1/gems/actionpack-3.2.9/lib/sprockets/assets.rake:29:in `block (2 levels) in <top (required)>'
       Tasks: TOP => environment
       (See full trace by running task with --trace)
       Precompiling assets failed, enabling runtime asset compilation

production.rb

config.assets.initialize_on_precompile = false