Build failure in nightlies

The last revision to lp:software-center introduced the following regression:

Traceback (most recent call last):
  File "setup.py", line 32, in <module>
    import softwarecenter.distro.ubuntu
  File "/home/buildd/work/tree/recipe-{debupstream}+r{revno}-{revno:packaging}/softwarecenter/distro/__init__.py", line 26, in <module>
    from softwarecenter.utils import UnimplementedError, utf8
  File "/home/buildd/work/tree/recipe-{debupstream}+r{revno}-{revno:packaging}/softwarecenter/utils.py", line 42, in <module>
    from enums import Icons, APP_INSTALL_PATH_DELIMITER
  File "/home/buildd/work/tree/recipe-{debupstream}+r{revno}-{revno:packaging}/softwarecenter/enums.py", line 316, in <module>
    from .version import VERSION, DISTRO, RELEASE, CODENAME
ImportError: No module named version
dh_auto_clean: python setup.py clean -a returned exit code 1
make: *** [clean] Error 1