klipper: remove duplicate items when loading from history
Due to a catastrophic bug existing in 5.27 beta and 5.27.0, there could be duplicate items in klipper's history file, so filter them out here.
The popup menu will try to read item->next_uuid()
in a loop to fill the menu, hence it's possible to create an infinite loop when there are duplicate items.
BUG: 466236 CCBUG: 465225 FIXED-IN: 5.27.4
Edited by Fushan Wen