Extra border spacing in sortable table in Safari 7.1.7

Extra border spacing in sortable table in Safari 7.1.7

I have a table with sortable rows (note that sortable() has been called on tbody as stated in the documentation). When I sort the rows, the border spacing gets bigger and bigger. This occurs when using "border-collapse: separate;" and setting a vertical spacing between the cells/rows, e.g. "border-spacing: 0 .3rem;".

I've created a very simple fiddle to demonstrate this:  http://jsfiddle.net/t6qzn5c8/
Repeatedly sort the rows and the space will keep growing.

At the start:

After repeated sorting:


This happens in Safari 7.1.7 running on OS X 10.9.5. This does not happen on Chrome 43, Firefox 39, IE 11, or Opera 30 running on Windows 7 Pro SP1.

This appears to be a bug - any suggestions?