TrinityCore/TrinityCore — comment on commit 1bd151dd472b3d64f9120931fa4ac0b765b6b3a2
File:  line 0
By nelegalno:

Until v4 the event and item had 14days duration and if you pickup the item in the wast day of the event you can complete it in any one of the 13 days after the even have ended. In v4 the changed it so the items are usable only during the event and they will disappear when the event is over thus the achievement is no longer completable after the event is over.
Since we are still on v3.3.5a the items should be usable for 14 days after they are obtained and the achievement should be completable during this period of time. Thus the condition that the "Holiday must be active" is incorrect.