CDN + Imagecache and protocol relative URLS

I see a lot of chatter regarding getting imagecache and cdn to play nicely together. I'm using the state of the art: CDN 6.x-2.6 and imagecache 6.x-2.0-rc1 (though I've also tied the latest dev release) however I'm still having issues. I'm using Cloudfront which supports https and so in my CDN settings I use the "protocol relative" url notation of //d1ud93p105xxxx.cloudfront.net.

Everything is working as expected except imagecache files which are being encoded as:

src="//%252Fd1ud93p105xxxx.cloudfront.net/sites/default/files/imagecache/profile_project/Fastlane-Crossroads.jpg"

Note the %252F

Does anybody have a solution for this?