If bind option is set in config.ru, puma will bind to both of:

• default host:port, or one set in puma.rb
• one given in config.ru

Specifically here
https://github.com/puma/puma/blob/master/lib/puma/configuration.rb#L101
it is adding one more bind option.

If one would need multiple binds, he could specify multiple bind options in config.ru.
But adding default bind while a explicit option given is kinda confusing.

Something like this:

binds = []
options.each do |key,val|
  if key.to_s[0,4] == "bind"
    binds << val
  end
end
binds.any? && @options[:binds] = binds

Makes sense?