Inconsistent/limited search results causing confusion

@dougbeal discovered a search bug and we were able to narrow it down.

From the homepage, searching for a term should return all pages that contain that term in the title or body. For example, searching "rocks" should return the wiki pages https://indieweb.org/Webmention_Rocks and and https://indieweb.org/Micropub_Rocks. Instead it's returning only https://indieweb.org/everything because it contains the word "rocks" in the body. This was making it difficult for him (and I'm sure others) to find pages on the wiki.

There appears to be a difference between the built-in MediaWiki search form at https://indieweb.org/Special:Search (in the main content area) and the search form that appears at the top right. If you search rocks in the top right form, it only shows the more-limited results. If you use the one in the main content area, you get the fuller, expected results. Note that the homepage, where Doug was searching from, only has the more-limited search form.

Debugging the URLs it appears the difference that causes this is the `redirs=0` URL param.

Compare:
https://indieweb.org/wiki/index.php?title=Special%3ASearch&redirs=0&search=rocks&fulltext=Search&ns0=1

with:
https://indieweb.org/wiki/index.php?title=Special%3ASearch&search=rocks&fulltext=Search

Start by comparing the homepage/top-right search form with Special:Search, using the two example URLs and the `redirs=0` difference described in the issue. Trace where the homepage form is configured and verify that searching “rocks” returns both Webmention_Rocks and Micropub_Rocks, matching the fuller Special:Search results.

Written by the indexing model from the issue text.