link-to-asset always returns a unique URL for concatenated .dieter assets #39

(dieter/link-to-asset "js/_vendor.js.dieter" dieter-options))
=> /assets/js/_vendor.js-09c7f64118df3c9ff04559a14b850259.dieter

If I curl this URL and then call link-to-asset multiple times afterwards, I always get a new URL. The expected behavior is for the URL to be unchanging after the asset has been generated once (because it's now using the generated file's md5 in the link instead of a timestamp).

Note that link-to-asset works as expected with non-concatenated assets.