Background

We were using the placeholder temporary users for permissions checks so that we could disallow anon (IP) users from editing (or whatever action) in the config, but still allow them to edit if the edit will create a temporary account. However, we're going to change that approach as summarised in T336187#9341749: we'll check against the anon (IP) user, and the config must be set to allow the * group to perform the action. We decided this so that other features wouldn't have to check against a temporary placeholder user. But it should also mean we can stop checking against a temporary placeholder user from EditPage too.

Notes

• EditPage may still need a placeholder temporary user for showing the correct user name in previews
• Permissions checks here include block checks. T353564: GlobalBlocking should use the same conditions as core to decide whether to check for XFF blocks is related, but should be solved separately from this regardless.