Return the calculated remote_ip or ip

This was an especially nasty bug introduced in 317f4e2, by the way that an instance of GetIp is not nil, but GetIp#to_s could sometimes return nil. Gross, huh?

actionpack/lib/action_dispatch/http/request.rb

@@ -157,7 +157,8 @@ module ActionDispatch
 
     # Originating IP address, usually set by the RemoteIp middleware.
     def remote_ip
-      @remote_ip ||= (@env["action_dispatch.remote_ip"] || ip).to_s
+      # Coerce the remote_ip object into a string, because to_s could return nil
+      @remote_ip ||= @env["action_dispatch.remote_ip"].to_s || ip
     end
 
     # Returns the unique request id, which is based off either the X-Request-Id header that can