tenderlove/nokogiri — comment on commit df274e6b8fb6f929be9313fc4d60174da3b08b67
File:  line 0
By yokolet:

The reporter of #560 defines a class that inherits Nokogiri::XML::Node. Descendants of Nokogiri::XML::Node are expected to behave like Nokogiri::XML::Element. So, the descendants should have all Element's methods that are available to use publicly. The []= method should be one of such public method.

This is why the change breaks issue 560.

If there's no problem, I'm going to get []= method back.