The python3 build failed on this, print is now a function and requires (), so the new line 233 should be 

> print ('WARNING: Not data found in volume to bound. Returning empty bounding box.')

At the top of mask.py, you should also add 

> from __future__ import division, print_function, absolute_import

That will make the print function in python2 behave like print in python3 (same for division and absolute_import, they are mostly in everyfile to ensure compatibility I guess).