Generic extractor fails: "object of type 'SetuptoolsVersion' has no len()"

[kingjon3377]

When I try to run euscan on most any package, it aborts instead of actually trying URLs. For example, here's the output of euscan euscan:

* app-portage/euscan-0.1.1-r1 [gentoo]

Ebuild: /usr/portage/app-portage/euscan/euscan-0.1.1-r1.ebuild
Repository: gentoo
Homepage: http://euscan.iksaif.net
Description: Ebuild upstream scan utility

 * SRC_URI is 'https://dev.gentoo.org/~hwoarang/distfiles/euscan-0.1.1.tar.gz'
 * Scanning: https://dev.gentoo.org/~hwoarang/distfiles/euscan-${PV}.tar.gz
 * Scanning: https://dev.gentoo.org/~hwoarang/distfiles
 * Generating version from 0.1.1
 * Brute forcing: https://dev.gentoo.org/~hwoarang/distfiles/euscan-${PV}.tar.gz
!!! euscan: object of type 'SetuptoolsVersion' has no len()