uscan had problems while searching for a new upstream version:
failed to parse XML: <dehs>
<errors>Malformed version line: version=5, only 'Version: X' is allowed when using version &gt;= 5</errors>
</dehs>
<package>python-tinycss2</package>
<debian-uversion>1.5.1</debian-uversion>
<debian-mangled-uversion>1.5.1</debian-mangled-uversion>
<upstream-version>1.5.1</upstream-version>
<upstream-url>https://pypi.debian.net/tinycss2/tinycss2-1.5.1.tar.gz</upstream-url>
<status>up to date</status>
<warnings>debian/watch version number is unrecognised</warnings>
</dehs>
</dehs>