How we handle K2 images hasn't changed, so there's nothing to fix.

We don't just develop K2 without actually using it heavily. We run sites with 1M+ uniques per month that have been with K2 since 2009. We obviously care for our sanity as well.

You're an edge case and I provided you with the solution already. In Linux systems "_GENERIC.jpg" is different to "_Generic.jpg".