importerror catkin_pkg

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Problem

I reinstalled ROS1 Kinetic on Ubuntu 16.04 since I realized I had been using pip, apt, and virtualenvs in the wrong way.

In my system environment, I installed ROS Kinetic following the guidelines which worked fine. However when I run

sudo rosdep init

I get:

Traceback (most recent call last):
  File "/usr/bin/rosdep", line 3, in <module>
    from rosdep2.main import rosdep_main
  File "/usr/lib/python2.7/dist-packages/rosdep2/__init__.py", line 45, in <module>
    from .lookup import RosdepDefinition, RosdepView, RosdepLookup, \
  File "/usr/lib/python2.7/dist-packages/rosdep2/lookup.py", line 41, in <module>
    from .rospkg_loader import RosPkgLoader
  File "/usr/lib/python2.7/dist-packages/rosdep2/rospkg_loader.py", line 37, in <module>
    import catkin_pkg.package
ImportError: No module named catkin_pkg.package

I had solved this before by installing it with pip instead of with apt but this apparently isn't the recommended method. I've also encountered other similar import errors before where python doesn't recognize packages installed with apt.

Details

dpkg -L python-catkin-pkg yields:

/.
/usr
/usr/share
/usr/share/doc
/usr/share/doc/python-catkin-pkg
/usr/share/doc/python-catkin-pkg/copyright
/usr/share/doc/python-catkin-pkg/changelog.Debian.gz
/usr/lib
/usr/lib/python2.7
/usr/lib/python2.7/dist-packages
/usr/lib/python2.7/dist-packages/catkin_pkg-0.4.6.egg-info
/usr/lib/python2.7/dist-packages/catkin_pkg-0.4.6.egg-info/top_level.txt
/usr/lib/python2.7/dist-packages/catkin_pkg-0.4.6.egg-info/dependency_links.txt
/usr/lib/python2.7/dist-packages/catkin_pkg-0.4.6.egg-info/entry_points.txt
/usr/lib/python2.7/dist-packages/catkin_pkg-0.4.6.egg-info/PKG-INFO
/usr/lib/python2.7/dist-packages/catkin_pkg-0.4.6.egg-info/requires.txt
/usr/bin
/usr/bin/catkin_find_pkg
/usr/bin/catkin_create_pkg
/usr/bin/catkin_test_changelog
/usr/bin/catkin_prepare_release
/usr/bin/catkin_package_version
/usr/bin/catkin_tag_changelog
/usr/bin/catkin_generate_changelog

dpkg -L ros-kinetic-catkin yields:

/.
/opt
/opt/ros
/opt/ros/kinetic
/opt/ros/kinetic/setup.bash
/opt/ros/kinetic/lib
/opt/ros/kinetic/lib/python2.7
/opt/ros/kinetic/lib/python2.7/dist-packages
/opt/ros/kinetic/lib/python2.7/dist-packages/catkin-0.7.11.egg-info
/opt/ros/kinetic/lib/python2.7/dist-packages/catkin
/opt/ros/kinetic/lib/python2.7/dist-packages/catkin/workspace_vcs.py
/opt/ros/kinetic/lib/python2.7/dist-packages/catkin/package_version.pyc
/opt/ros/kinetic/lib/python2.7/dist-packages/catkin/tidy_xml.py
/opt/ros/kinetic/lib/python2.7/dist-packages/catkin/cmake.py
/opt/ros/kinetic/lib/python2.7/dist-packages/catkin/tidy_xml.pyc
/opt/ros/kinetic/lib/python2.7/dist-packages/catkin/init_workspace.py
/opt/ros/kinetic/lib/python2.7/dist-packages/catkin/terminal_color.py
/opt/ros/kinetic/lib/python2.7/dist-packages/catkin/test_results.py
/opt/ros/kinetic/lib/python2.7/dist-packages/catkin/environment_cache.py
/opt/ros/kinetic/lib/python2.7/dist-packages/catkin/workspace.py
/opt/ros/kinetic/lib/python2.7/dist-packages/catkin/find_in_workspaces.py
/opt/ros/kinetic/lib/python2.7/dist-packages/catkin/find_in_workspaces.pyc
/opt/ros/kinetic/lib/python2.7/dist-packages/catkin/package_version.py
/opt/ros/kinetic/lib/python2.7/dist-packages/catkin/builder.pyc
/opt/ros/kinetic/lib/python2.7/dist-packages/catkin/init_workspace.pyc
/opt/ros/kinetic/lib/python2.7/dist-packages/catkin/__init__.py
/opt/ros ...