Ask HN: Git for SVG?

I'm creating SVG maps programmatically from geographic data and I want to post-process some of the elements in an editor (mostly simple operations: translate, rotate, scale). The rub: when I update the data and regenerate the map (SVG), I want to easily apply my manual edits on top of the new auto-generated version. Something akin to "git merge" but for SVG, ideally with a graphical merge tool!

Any thoughts or pointers at all are welcome. Thanks a lot :)