Only set iodine as default handler if ENV['RACK_HANDLER'] is not set
Only set iodine as default handler if ENV['RACK_HANDLER'] is not set

Rack appears to use this env var before selecting from a final list as per these docs https://www.rubydoc.info/gems/rack/Rack/Handler#default-class_method

boazsegev/iodine,boazsegev/iodine,boazsegev/iodine