When trying to use the libsass filter, I get the following error:
TypeError: compile() got unexpected keyword argument(s) 'image_path'
It appears that libsass (as in the C++ library) hasn't supported image_path for nearly a year (sass/libsass#834) and now the latest version of libsass-python has dropped support for arbitrary kwargs in compile (sass/libsass-python#109) - thus causing an error as image_path isn't a valid kwarg.
Installing libsass<0.10 works around this issue.