plug-in model unit tests from python shell not always working?

[richardh]

from sasmodels.model_test import run_one
run_one("~/.sasview/plugin_models/hollow_cylinder_new.py")

got this to work on a simple only .py model, but but my hollow_cylinder_new.py failed with an "index out of range", see below. The identical code passed tests ok from cmd window with
python -m sasmodels.model_test hollow_cylinder_new

from sasmodels.model_test import run_one
run_one("~/.sasview/plugin_models/hollow_cylinder_new.py")
Traceback (most recent call last):

File "<input>", line 1, in <module>
File "C:\stfc\sasview4\sasmodels\sasmodels\model_test.py", line 293, in run_one

if not suite._tests[0].info.tests:

IndexError?: list index out of range

[pkienzle]

See #706