wstool cannot import rosinstall

edit

On Ubuntu Precise, I get the following error when trying to run wstool up to create a new workspace:

$ wstool up
ERROR: Cannot find required rosinstall library version, check your installation (also of vcstools) is up-to-date. One frequent cause is that rosinstall 0.5 is still installed in /usr/local/lib.
cannot import name urlopen_netrc

I've checked, and I have the latest versions of the wstool, vcstools and rosinstall libraries:

$ dpkg -l python-wstool python-vcstool python-bloom python-rosinstall
Desired=Unknown/Install/Remove/Purge/Hold
| Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend
|/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad)
||/ Name                Version             Description
+++-===================-===================-======================================================
ii  python-bloom        0.5.9-1             Bloom is a release automation tool.
ii  python-rosinstall   0.7.3-1             The installer for ROS
ii  python-vcstool      0.1.6-1             vcstool provides a command line tool to invoke vcs com
ii  python-wstool       0.1.3-1             workspace multi-SCM commands

If I try to import the rosinstall module in ipython, I get the following stacktrace:

In [1]: import rosinstall
---------------------------------------------------------------------------
ImportError                               Traceback (most recent call last)
/home/hendrix/junior/src/<ipython-input-1-c1a82de03eac> in <module>()
----> 1 import rosinstall

/usr/lib/pymodules/python2.7/rosinstall/__init__.py in <module>()
     31 # POSSIBILITY OF SUCH DAMAGE.
     32 
---> 33 import wstool.helpers

/usr/lib/pymodules/python2.7/wstool/helpers.py in <module>()
     35 import codecs
     36 import subprocess
---> 37 from wstool.config_elements import SetupConfigElement
     38 
     39 ROSINSTALL_FILENAME = ".rosinstall"

/usr/lib/pymodules/python2.7/wstool/config_elements.py in <module>()
     40 
     41 from wstool.common import samefile, MultiProjectException
---> 42 from wstool.config_yaml import PathSpec
     43 from wstool.ui import Ui
     44 

/usr/lib/pymodules/python2.7/wstool/config_yaml.py in <module>()
     33 import os
     34 import yaml
---> 35 from vcstools.common import urlopen_netrc
     36 from wstool.common import MultiProjectException
     37 

ImportError: cannot import name urlopen_netrc

I'm pretty sure that I only have rosinstall installed from debs, and the paths listed in the stack trace agree. Any thoughts?