Bug#896309: python-cfflib: cfflib fails to import

[Helmut Grohne <helmut@subdivi.de>]

Package: python-cfflib
Version: 2.0.5-2
Severity: serious
User: helmutg@debian.org
Usertags: python-import

After installing python-cfflib importing the module cfflib
into a python interpreter fails with the following error:

Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "/usr/lib/python2.7/dist-packages/cfflib/__init__.py", line 2, in <module>
    from loadsave import *
  File "/usr/lib/python2.7/dist-packages/cfflib/loadsave.py", line 6, in <module>
    import cfflib2 as cf
  File "/usr/lib/python2.7/dist-packages/cfflib/cfflib2.py", line 10, in <module>
    from util import *
  File "/usr/lib/python2.7/dist-packages/cfflib/util.py", line 18, in <module>
    raise ImportError("Failed to import nibabel from any known place")
ImportError: Failed to import nibabel from any known place

The vast majority of import failures is attributed to missing dependencies.
Often times that manifests as an ImportError or ModuleNotFoundError.
Typically, dependencies should be inserted by dh-python via ${python:Depends}
or ${python3:Depends}. Thus a missing dependency can be caused by incomplete
install_requires in setup.py. Sometimes a missing dependency of a dependency
is the cause, in such cases this bug should be reassigned.

Helmut