How to search for wikis that don't have a particular extension installed?

extensions

#1

I would like to figure out an easy way to get result of wikis that don’t have a particular extension installed. For now ConfirmEdit and OpenID.


#2

Wikimedia wikis, or wikis in general?


#3

Yes, wikis in general.


#4

Wikiapiary has a ‘has extension’ property that I’m guessing could be used to query this. (I think it involves querying subobjects, and I can’t remember how to do that.)