Running: rake assets:precompile
rake aborted!
   undefined method `match' for nil:NilClass
   /tmp/build_3nnbzpfmnjpns/vendor/bundle/ruby/1.9.1/gems/mongoid-3.0.21/lib/mongoid/sessions/mongo_uri.rb:49:in `initialize'

完整的堆栈跟踪可以在http://pastebin.com/8YcJHEmS找到

但是,如果我从我的Gemfile中删除Unicorn,则资产编译成功.查看Mongoid代码,我可以看到,当mongoid.yml文件被解析时,会发生错误,但是我无法弄清楚Unicorn为什么会导致失败.
我的mongoid.yml文件如下所示：

production:
  sessions:
    default:
      uri: <%= ENV['MONGOHQ_URL'] %>
      options:
        skip_version_check: true
        safe: true

和我的宝石：

source 'https://rubygems.org'
ruby '1.9.3'

gem 'rails','3.2.11'
gem 'thin'

group :assets do
  gem 'sass-rails','~> 3.2'
  gem 'coffee-rails','~> 3.2'
  gem 'uglifier','>= 1.0.3'
  gem "twitter-bootstrap-rails",'>=2.1.8'
  gem "bootstrap_form"

end

gem "jquery-rails"
gem 'jquery-ui-rails',"3.0.1"

gem 'newrelic_rpm'
gem "httparty"
gem "resque"
gem "resque-loner"
gem "unicorn","4.4.0"
gem "mongoid","~> 3.0.0"
gem "mongo","~> 1.7.0"
gem "bson","~> 1.7"
gem "bson_ext","~> 1.7"
gem 'less-rails',"~> 2.2"
gem 'therubyracer','>= 0.11.1'
gem 'libv8','~> 3.11.8'
gem 'devise','~> 2.1.2'
gem 'devise_invitable','~> 1.0.0'
gem 'bootstrap_form'
gem 'font-awesome-rails'
gem 'omniauth'
gem 'omniauth-facebook'
gem 'kaminari'
gem 'mongoid_search'

你有什么想法是什么原因造成的？