It does preserve it - you should just need to fill in something in the Summary field, press Next, and press "No, I need to report a new bug", and then you should find that your text is still in the "Further information" box.
It does preserve it - you should just need to fill in something in the Summary field, press Next, and press "No, I need to report a new bug", and then you should find that your text is still in the "Further information" box.