Background
It seems there are several disjunctions between wgContentNamespaces and wgNamespacesToBeSearchedDefault. The latter is what is reflected as "Content" in the Special:Search page.
This was noticed because "Risotto" doesn't return any results on en.wikibooks, even though there is the page Cookbook:Risotto. I have created a diff list between the two variables using P5740
- Not searching 102 for aswikisource
- Not searching [100] for bnwikisource
- Not searching 102 for enwikibooks: Cookbook namespace
- Not searching 110 for enwikibooks: WikiJunior namespace
- Not searching [102, 110] for fawikibooks (کتاب_آشپزی cookbook) and ویکی_کودک wikijunior)
- Not searching 100 for hewikisource
- Not searching 106 for hewikisource
- Not searching 110 for hewikisource
- Not searching [102] for hrwiki
- Not searching [104] for ltwikipedia: vikiprojektas (wikiprojects ? why is that in contentnamespaces ?)
- Not searching [102] for srwikibooks: кувар (cookbook)
- Not searching [100] for srwikisource
- Not searching [100, 110] for trwikibooks: yemek (cookbook) and vikiçocuk (wikijunior)
Some of these might be desirable, but likely most not.
Success criteria
Reach out to the communities affected and ask if they would like the setting to be changed. Create subtasks to track the technical configuration changes requested (if any)
Timeline
This was unplanned work. The actual change should be technically trivial, reaching out and discussing with communities will take a little longer (weeks at minimum between informing, consensus, and responding)