Comma-separated list valid in Content-Type header?

Question

An RSS feed provider recently started sending this in its response headers:

Content-type: application/rss+xml, text/xml; charset=UTF-8

To support this provider, I needed to change a line in a feed integration package (SimplePie)

1. Is the provider "wrong?"
2. Would it be "wrong" to change a community-maintained package to support this header?

Answer 1

1. Yes - Content-Type doesn't take a list. Apparently somebody confused "Content-Type" with "Accept".
2. Yes.