This is an old question but there is some newer guidance in PEP 565 that to turn off all warnings if you're writing a python application you should use:
import sys
import warnings
if not sys.warnoptions:
warnings.simplefilter("ignore")
The reason this is recommended is that it turns off all warnings by default but crucially allows them to be switched back on via python -W
on the command line or PYTHONWARNINGS
.