If a page does not exist, and someone just created it by [[Special:ChangeContentModel]], even if it matched [[MediaWiki:Titleblacklist]], it will still be created.
Eg. Add a line .* in [[MediaWiki:Titleblacklist]], then let other user (who is not a sysop) open [[Special:ChangeContentModel]], input any title, then change the model to whatever you like, then the page is created.
Steps to test: (all on testwiki)
- Revoke tboverride from template editors (https://gerrit.wikimedia.org/r/654449/)
- Add User:DannyS712\/Bug.* to title blacklist
- Grant template editor rights to an alternate test account
- Switch to using that alternate test account
- Try to create User:DannyS712/Bug 1 manually, to confirm its properly blacklisted
- Try to create it via Special:ChangeContentModel, to confirm the bug exists
- <deploy fix>
- Try to create User:DannyS712/Bug 2 via Special:ChangeContentModel, should fail
includes/content/ContentModelChange.php added in T107174: Add an API action to just change content model/rMW0789d1568d76: Add a ContentModelChange helper, and an api module that uses it