The URI in question can be considered as a Same-Document Reference. As the current xml:base in effect does not match the URI of the document, this can lead to inconsistent and non-interoperable behavior between different clients.
Consider changing the xml:base to reference the either the document itself, or the parent directory of the document referenced.
For example, change:
<link href="." xml:base="http://example.com/blog/" />
<link href="." xml:base="http://example.com/blog/feed.atom" />
<link href="blog/" xml:base="http://example.com/" />
Not clear? Disagree?
You might be able to find help in one of these fine resources.