Last modified: 2011-03-13 18:05:55 UTC
The string !("autoconfirmed" in user_groups) does not filter out editors in the "confirmed" usergroup. Since entrance to this usergroup is granted to allow a newbie acting in good faith to bypass the 4/10 restrictions on moving pages and editing through semi-protection, it should naturally also allow them to bypass any edit filter that only blocks newbies. There would be no real harm in doing this, as any user could do as much harm by exercising the typical autoconfirmed rights as they could by bypassing the filter, and any user smart enough to make a reasonable request for confirmation also knows he can just wait four days.
!("autoconfirmed" in user_groups) means exactly that — the user is not in the autoconfirmed group. I am certainly not special-casing this to mean something else.
