менеджер обновления перестал работать с “ImportError: Никакой модуль, названный 'ros_buildfarm'”

то, когда я пытался обновить ubuntu 16.04 I, получило эту ошибку:

sos@sos:~$ sudo update-manager 
/usr/bin/update-manager:28: PyGIWarning: Gtk was imported without specifying a version first. Use gi.require_version('Gtk', '3.0') before import to ensure that the right version gets loaded.
  from gi.repository import Gtk
/usr/lib/python3/dist-packages/UpdateManager/UnitySupport.py:29: PyGIWarning: Dbusmenu was imported without specifying a version first. Use gi.require_version('Dbusmenu', '0.4') before import to ensure that the right version gets loaded.
  from gi.repository import Dbusmenu, Unity
/usr/lib/python3/dist-packages/UpdateManager/UnitySupport.py:29: PyGIWarning: Unity was imported without specifying a version first. Use gi.require_version('Unity', '7.0') before import to ensure that the right version gets loaded.
  from gi.repository import Dbusmenu, Unity
Traceback (most recent call last):
  File "/usr/bin/apt.py", line 21, in <module>
    from ros_buildfarm.wrapper.apt import main
ImportError: No module named 'ros_buildfarm'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/bin/update-manager", line 38, in <module>
    from UpdateManager.UpdateManager import UpdateManager
  File "/usr/lib/python3/dist-packages/UpdateManager/UpdateManager.py", line 57, in <module>
    from .MetaReleaseGObject import MetaRelease
  File "/usr/lib/python3/dist-packages/UpdateManager/MetaReleaseGObject.py", line 25, in <module>
    from .Core.MetaRelease import MetaReleaseCore
  File "/usr/lib/python3/dist-packages/UpdateManager/Core/MetaRelease.py", line 25, in <module>
    import apt
  File "/usr/bin/apt.py", line 25, in <module>
    from ros_buildfarm.wrapper.apt import main
ImportError: No module named 'ros_buildfarm'
Error in sys.excepthook:
Traceback (most recent call last):
  File "/usr/bin/apt.py", line 21, in <module>
   from ros_buildfarm.wrapper.apt import main
ImportError: No module named 'ros_buildfarm'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/apport_python_hook.py", line 63, in apport_excepthook
    from apport.fileutils import likely_packaged, get_recent_crashes
  File "/usr/lib/python3/dist-packages/apport/__init__.py", line 5, in <module>
    from apport.report import Report
  File "/usr/lib/python3/dist-packages/apport/report.py", line 30, in <module>
    import apport.fileutils
  File "/usr/lib/python3/dist-packages/apport/fileutils.py", line 23, in <module>
    from apport.packaging_impl import impl as packaging
  File "/usr/lib/python3/dist-packages/apport/packaging_impl.py", line 23, in <module>
    import apt
  File "/usr/bin/apt.py", line 25, in <module>
    from ros_buildfarm.wrapper.apt import main
ImportError: No module named 'ros_buildfarm'

Original exception was:
Traceback (most recent call last):
  File "/usr/bin/apt.py", line 21, in <module>
    from ros_buildfarm.wrapper.apt import main
ImportError: No module named 'ros_buildfarm'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/bin/update-manager", line 38, in <module>
    from UpdateManager.UpdateManager import UpdateManager
  File "/usr/lib/python3/dist-packages/UpdateManager/UpdateManager.py", line 57, in <module>
    from .MetaReleaseGObject import MetaRelease
  File "/usr/lib/python3/dist-packages/UpdateManager/MetaReleaseGObject.py", line 25, in <module>
    from .Core.MetaRelease import MetaReleaseCore
  File "/usr/lib/python3/dist-packages/UpdateManager/Core/MetaRelease.py", line 25, in <module>
    import apt
  File "/usr/bin/apt.py", line 25, in <module>
    from ros_buildfarm.wrapper.apt import main
ImportError: No module named 'ros_buildfarm'