cloudinary:sync_assets with custom static_images_dir doesn't work

The code that works out if it should use the static hash name looks the file up in the static metadata with
`if type == :asset && @metadata["images/#{source}"]`

my `static_images_dir` is set to `["assets/images/email"]` as I only want email assets to be done by cloudinary.

The creates a meta data file containing paths such as `emails/twitter.png`, so when the meta data is looked for it doesn't find it because its looking for `images/emails/twitter.png`?