Not only do the namespace prefixes "all:" "All:" and "All: " all behave differently,
but they also differ from the setting of at Special:Search Advanced "All"
- Search for the two words `phenomenal inhouse' on Wikipedia.
- On the search results page, set Advanced to All namespaces, and press Search. You get six hits, in five different namespaces.
- In the search box insert "all:" with or without a space. You lose the two from the File namespace.
- Now try "All: " with capital "A" and a space. You lose article space.
- Now try "All:" with no space. You lose your query.
Should this be documented, or is it unintended?