Also, add tests covering this and the previous bug fixes in this code
(T259818, T261706).
Note that the test data added in tests/cases/ doesn't exactly match
the entire configuration of the wiki, only the parts we want to cover.
This is unlike the data in tests/data/, which was literally copied
from the relevant wikis, and which is used as input for other tests.
Bug: T265500
Change-Id: I29a59a5952f6dc9fb5910434bb6bcc9dcdaa01a9
