I didn't think it was a bug as if done from an angle (ie using 1,3,7 or 9) you could kick the item out. Doing it straight on (2,4,6, or 8) produced a message saying it wouldn't work. Got a whole bunch of slings stuck in the end. Being monk you could just kick the rock out from underneath the item. Got fairly confusing when you try to step over the item and you character hits their head on a wall... found the attachment button, uploading .svg
EDIT: or not, file too large...