Searchery Doesn't Work in Latest Minefield Nightly Builds

I'm using the Nightly Builds of Firefox 3, and all of a sudden, Searchery has stopped working properly. Now, when I click on a search engine in this list, instead of opening the search, it simply places the search URL in the Location bar. In order to open the page with the search, I then have to hit enter. Very irritating, since I love Searchery. I have checked to make sure that it isn't an extension conflict by installing a clean profile with only Searchery installed, but the problem still occurs.
Mozilla/5.0 (Windows; U; Windows NT 6.0; en-US; rv:1.9.1b1pre) Gecko/20080927033433 Minefield/3.1b1pre ID:20080927033433