Created attachment 321949 [details]
When animating a circle on top of other circles, the background is not drawn correctly.
If the circles do not have a "scale" transform on the g object, it draws fine.
Please see fiddle https://jsfiddle.net/6cbvxzte/3/
Fiddle when it works fine (without scale): https://jsfiddle.net/6cbvxzte/
It started to occur in Safari 6.2 and doesn't draw correctly in any newer version from what I have seen.
Have not been able to reproduce in Chrome (also older versions).
I have tried to find a bug for this in the database so accept my apology if there is one already.
Confirmed with Safari 11.