Saving SVGs with clip paths adds extra groups

When an AI file containing a shape (test.ai) with an image fill is exported as SVG (test.svg), a SVG group is created containing the shape's path with clipped sub-groups, defined using <defs>, containing the image. All well and good, apart from the fact that the shape's path is duplicated -- once in a <defs> element for clipping, once as the actual <path> -- and I suspect there's scope for optimisation.

If the saved SVG (test.svg) is resaved (as test1.svg) the groups above are wrapped in extraneous <g> elements -- one before each nested <defs> element, resulting in three additional nested groups. If test1.svg is saved again (as test2.svg) another three group elements are added.

Ongoing saving and opening a SVG eventually results in AI warning "There are too many nested groups than allowed in Illustrator. The file may not open correctly." and the shape's image fill is lost.