footnote ancor (id-attribute) not rendered

[philister]

foo[1]

bar

fn1. Not exclusivly foo, als foobar.

It will not render the id-attribute of the p-tag.

Redcloth is working correct:
text= "foo[1]\n\nbar\n\nfn1. Not exclusivly foo, als foobar."; RedCloth.new(text).to_html
results in:
<p>foo<sup class="footnote" id="fnr1"><a href="#fn1">1</a></sup></p>\n<p>bar</p>\n<p class="footnote" id="fn1"><a href="#fnr1"><sup>1</sup></a> Not exclusivly foo, als foobar.</p>