Author: rspitzbart

Description:
The field wl_notificationtimestamp in the watchlist table is set back to NULL
when visiting the page but set back to 0 when the 'Mark all pages visited'
button on the Special:Watchlist page is clicked.

The UserMailer.php checks for entries that have this timestamp set to NULL
rather than NULL or 0, so clicking the button doesn't re-enable emails.

Version: 1.7.x
Severity: major
Platform: PC