The actual use of this option is `gem 'pg', platforms: :jruby`, not `gem 'pg', platform: :jruby`. This is a problem since gems that were not specific to the current Ruby platform were getting added to the gem list. This was specially problematic because multiple DB adaptors were getting into the gem list when the same adaptor was being used for different platforms, which caused "More than one adapter gem found in Gemfile!" to be raised. Example: ``` gem 'activerecord-jdbcpostgresql-adapter', platforms: :jruby gem 'pg', platforms: :mri ```
It's normal to have in your Gemfile more than one platform (JRuby, MRI etc). Railbrazer, though, is not considering it when choosing the database adapter. It's also raising an exception on Gemfiles such as the following: ``` gem 'pg', platform: :mri gem 'activerecord-jdbcpostgresql-adapter', platform: :jruby ``` With this change, we only select the gems that are defined for the current platform.