Cannot cancel natural onTrailerAttach events

[ArranTuna]

Describe the bug
If you attach a trailer to a vehicle naturally (by using a towtruck), cancelEvent() does not work.

Also for attaching a trailer to a Truck.

To Reproduce

testcar = createVehicle (450, 0,0,3.5)
function detachTrailer(theTruck)
    if source == testcar then
        outputDebugString("Cancel attached testcar",3)
        cancelEvent()
    end
 end
addEventHandler("onTrailerAttach", getRootElement(), detachTrailer)

Expected behavior
cancelEvent should stop the attachment of trailer.

MTA Client: client v1.5.5-release-14007 (@patrikjuvonen verified)

MTA Server: Server v1.5.5-release-14007 (@patrikjuvonen verified)

Additional context
From https://bugs.mtasa.com/view.php?id=8008