...

How about excluding all redirects from the search results, that lead

to

...

an article that is already listed?

That would do for most, but not all cases I was aiming for.

But it would be much easier :-)

For example, if there's is an article Wikipedia:Wikipedians/Zimbabwe that used to

be

at Wikipedians/Zimbabwe, I get a redirect to an article in the non-article namespace.

That's true. At the moment I sometimes use these redirects to find pages in the wikipedia namespace. I think those few redirects wouldn't be too annoying.

A similar situation occurs if the article on Harare used to be at Zimbabwe/Harare.

Why? If you search for Harare and Zimbabwe/Harare is a redirect to that page it will be excluded. - But maybe I didn't understand you right.

Kurt