Why won't my want give me an upgraded staff?

I have a +3 want of lightning and an unupgraded staff, and according to the wiki, I should end up with a +2 staff, but it says I'll only get a level 1 staff. Why? I tried this on a different run, and it actually gave me an unupgraded staff, it's not just the prompt being wrong. I'm playing the latest version of Shattered Pixel Dungeon.