python backend gets confused by version strings including '-'

I get the following error message when trying to run pkgme which has a '-' in the version in setup.py:

ERROR: debuild --no-lintian -S failed with returncode 1. Output:
 | This package has a Debian revision number but there does not seem to be
 | an appropriate original tar file or .orig directory in the parent directory;
 | (expected one of framingham_0.1.orig.tar.gz, framingham_0.1.orig.tar.bz2,
 | framingham_0.1.orig.tar.lzma, framingham_0.1.orig.tar.xz or framingham-0.1.orig)
 | continue anyway? (y/n) Use of uninitialized value $ans in pattern match (m//) at /usr/bin/debuild line 995.

TEST-CASE:
 - Download tarball from https://myapps.developer.ubuntu.com/dev/apps/579/
 - rm -r debian/
 - pkgme

Removing the '-' from the version number makes it work.