"Asset filtered out... select2.png" error message cause

If you see this following message coming from tests or usage of a plugin
against develop:

Asset filtered out and will not be served: add
Rails.application.config.assets.precompile += %w( select2.png ) to
config/initializers/assets.rb and restart your server

… then you probably need to update the plugin registration initialiser

The deprecation warning/compatibility layer was removed in develop
recently for 1.13. I've seen a few plugins with tests failing for this
reason, so try to get it updated in time for 1.13.0.

··· -- Dominic Cleal dominic@cleal.org