[bug] Can't cancel swap once an item has been hovered over

Describe the bug

When using the Swap plugin, it's impossible to cancel a swap once the swap threshold has been met for an item. You can't drag the item back to its original place to prevent a swap. This happens with or without the revertOnSpill: true option.

To Reproduce Steps to reproduce the behavior:

1. Go to https://sortablejs.github.io/Sortable/#swap
2. Drag "Item 1" to hover over "Item 2", triggering Item 2 to get highlighted. Don't drop "Item 1", but instead try to prevent a swap by moving Item 1 back to its original place.
3. See: It's not possible to prevent a swap.

Expected behavior

Dragging Item 1 back to its original place, or off of the list, should deactivate the swap.

Information

Sortable.version == 1.10.2

I didn't include a code sandbox since it's visible with Sortable.js's own Github site.

Thank you so much for your work on this library!