rosinstall not working after ROS package upgrade

edit

As of this AM, I updated all the deb packages on my 16.04 machine, and now wstools 0.1.16 does not work. 0.1.12 still does. With 0.1.16, I get this when I run rosws:

$ rosws up
Traceback (most recent call last):
  File "/usr/bin/rosws", line 52, in <module>
    import rosinstall.rosws_cli
  File "/usr/lib/python2.7/dist-packages/rosinstall/__init__.py", line 33, in <module>
    import wstool.helpers
  File "/usr/lib/python2.7/dist-packages/wstool/helpers.py", line 37, in <module>
    from wstool.config_elements import SetupConfigElement
  File "/usr/lib/python2.7/dist-packages/wstool/config_elements.py", line 43, in <module>
    from wstool.config_yaml import PathSpec
  File "/usr/lib/python2.7/dist-packages/wstool/config_yaml.py", line 37, in <module>
    import wstool.config
  File "/usr/lib/python2.7/dist-packages/wstool/config.py", line 35, in <module>
    from wstool.config_elements import AVCSConfigElement, OtherConfigElement, SetupConfigElement
ImportError: cannot import name AVCSConfigElement