Adding image to RSS breaks feed

Checking the option “Add image to RSS/RSS2 feeds:” breaks my RSS feeds. Specifically, or perhaps only, in combination with Jetpack.

Jetpack adds georss namespaces to the feed, this plugin ads a yahoo image namespace. But, without this namespace followed by a new line. Jetpack ads its namespaces without starting with an enter and, as a result, the namespaces are ‘stuck’ together, resulting in a feed that does not validate.