setup.py: reload __version__.py after writing it. write_version loads __version__.py before writing it (see 7eb694a1c1af), so we have to explicitly reload it to use the correct version. Problem diagnosed by Christian Ebert.

<item>
    <title>#tag|escape#</title>
    <link>{urlbase}{url}rev/{node|short}</link>
    <description><![CDATA[#tag|strip|escape|addbreaks#]]></description>
    <pubDate>#date|rfc822date#</pubDate>
</item>