title: Already initialized constant warnings after Rails 4.2 upgrade
body: <p>After upgrading a simple Rails 4.1.8 application to Rails 4.2.0, I see lots of warnings about already initialized constants coming out of the PostgreSQL adapter:</p>
  
  <pre><code>/path/to/my/torquebox-3.1.1/jruby/lib/ruby/gems/shared/gems/activerecord-4.2.0/lib/active_record/connection_adapters/postgresql/array_parser.rb:6 warning: already initialized constant DOUBLE_QUOTE
  /path/to/my/torquebox-3.1.1/jruby/lib/ruby/gems/shared/gems/activerecord-4.2.0/lib/active_record/connection_adapters/postgresql/array_parser.rb:7 warning: already initialized constant BACKSLASH
  /path/to/my/torquebox-3.1.1/jruby/lib/ruby/gems/shared/gems/activerecord-4.2.0/lib/active_record/connection_adapters/postgresql/array_parser.rb:8 warning: already initialized constant COMMA
  /path/to/my/torquebox-3.1.1/jruby/lib/ruby/gems/shared/gems/activerecord-4.2.0/lib/active_record/connection_adapters/postgresql/array_parser.rb:9 warning: already initialized constant BRACKET_OPEN
  /path/to/my/torquebox-3.1.1/jruby/lib/ruby/gems/shared/gems/activerecord-4.2.0/lib/active_record/connection_adapters/postgresql/array_parser.rb:10 warning: already initialized constant BRACKET_CLOSE
  </code></pre>
  
  <p>Is this expected or does it indicate a problem with the new version of Rails (presumably running under JRuby)? Any way to properly fix these warnings (other than just silencing them)?</p>