Yeh I came across this ages ago myself. it was jammed in the crab at the top, so I de-rigged it before someone tried prussicing it as the lower pitch was rigged, I could see a potential accident. I did not know who's it was so I left it on the ledge hoping the owner would retrieve it as I had no space in my bag.
Then I completely forgot about it, as its kind of routine for me to come across a rope jammed on that pitch.