Change 932292 had a related patch set uploaded (by Tchanders; author: Tchanders):

[mediawiki/core@master] Add temporary users to a 'temp' group, and stop adding them to 'user'

https://gerrit.wikimedia.org/r/932292

What needs doing?

Temp/user/named groups:

• In UserGroupManager::getUserImplicitGroups, add temporary users to a 'temp' group, and stop adding them to the 'user' group
• Keep 'named' group as future-proofing for if temp users do get the 'user' group

User rights:

• Throw an error from Special:Userrights explaining that temporary users do not have groups

Autoconfimred and autopromote:

• Prevent temp users from being reported as belonging to autopromote and autopromote-once groups (they already aren't if checking via PermissionManager)

UserGroupManager:

• Throw an error for UserGroupManager::addUserToGroup if user is temp
• Check if any other parts of UserGroupManager need updating to early return for temp, or whether these are safe to leave as is
• Ensure UserGroupManager::addUserToGroup is not called on temporary users from WMF deployed code
• Check that User::addGroup (deprecated, replaced by UserGroupManager::addUserToGroup) is not called on temporary users from WMF deployed code

Documentation:

• Record on release notes (breaking changes) that UserGroupManager::addUserToGroup throws an error for temporary users
• Update https://www.mediawiki.org/wiki/Help:Temporary_accounts/How_it_works with these changes

This is ticket is tracking the subtasks, so moving to blocked/stalled while we work on those.