I started playing around with this in IPBlockForm::doBlock(). I'm having trouble finding a quick way to grab the Title object for the userpage of the person you're blocking though, as User::addWatch() requires a Title object to watch.

ayg wrote:

User::getUserPage()?

Works for the current $wgUser, yes. There's not necessarily a user object for the blocked user. Is if you're blocking a logged in user, but not an anonymous one.

ayg wrote:

Why can't you get a User object for an anonymous user?

Created attachment 4882
Patch against r34306

Implement "watchlist this user" on [[Special:Blockip]]. Adds new system message ipbwatchuser for the label.

Attached:

ayg wrote:

Werdna seems to have applied this with r34307.