Bug#781270: python3-apt: Exception gives Ubuntu-related link on Debian

["W. Martin Borgert" <debacle@debian.org>]

Package: python3-apt
Version: 0.9.3.11
Severity: minor

In apt/package.py:1063 is a link that is probably fine for Ubuntu,
but wrong for Debian:

    except HTTPError:
        res = _("The list of changes is not available yet.\n\n"
                "Please use http://launchpad.net/ubuntu/+source/%s/";
                "%s/+changelog\n"
                "until the changes become available or try again "
                "later.") % (src_pkg, src_ver)
        return res if isinstance(res, unicode) else res.decode("utf-8")