"uvt-simplestreams-libvirt purge" fails on precise

$ uvt-simplestreams-libvirt purge
Warning: this CLI is experimental and may change.
Traceback (most recent call last):
  File "/usr/bin/uvt-simplestreams-libvirt", line 110, in <module>
    main()
  File "/usr/bin/uvt-simplestreams-libvirt", line 106, in main
    args.func(args)
  File "/usr/bin/uvt-simplestreams-libvirt", line 67, in main_purge
    uvtool.libvirt.simplestreams.purge_pool()
  File "/usr/lib/python2.7/dist-packages/uvtool/libvirt/simplestreams.py", line 135, in purge_pool
    volume.delete()
TypeError: delete() takes exactly 2 arguments (1 given)

Workaround:

$ python -mpdb /usr/bin/uvt-simplestreams-libvirt purge
> /usr/bin/uvt-simplestreams-libvirt(24)<module>()
-> from __future__ import print_function
(Pdb) c
Warning: this CLI is experimental and may change.
Traceback (most recent call last):
  File "/usr/lib/python2.7/pdb.py", line 1314, in main
    pdb._runscript(mainpyfile)
  File "/usr/lib/python2.7/pdb.py", line 1233, in _runscript
    self.run(statement)
  File "/usr/lib/python2.7/bdb.py", line 387, in run
    exec cmd in globals, locals
  File "<string>", line 1, in <module>
  File "/usr/bin/uvt-simplestreams-libvirt", line 24, in <module>
    from __future__ import print_function
  File "/usr/bin/uvt-simplestreams-libvirt", line 106, in main
    args.func(args)
  File "/usr/bin/uvt-simplestreams-libvirt", line 67, in main_purge
    uvtool.libvirt.simplestreams.purge_pool()
  File "/usr/lib/python2.7/dist-packages/uvtool/libvirt/simplestreams.py", line 135, in purge_pool
    volume.delete()
TypeError: delete() takes exactly 2 arguments (1 given)
Uncaught exception. Entering post mortem debugging
Running 'cont' or 'step' will restart the program
> /usr/lib/python2.7/dist-packages/uvtool/libvirt/simplestreams.py(135)purge_pool()
(Pdb) volume.delete(0)
0