misleading warning during papermill run

[rgbkrk]

With the following papermill run,

$ papermill -p x 1 -p y 70 template.ipynb out.ipynb
/usr/local/lib/python2.7/site-packages/jupyter_client/connect.py:157: RuntimeWarning: Failed to set sticky bit on u'/var/folders/kd/cylz4mhs1_9cpsjh0_c_gzfr0000gn/T': [Errno 1] Operation not permitted: '/var/folders/kd/cylz4mhs1_9cpsjh0_c_gzfr0000gn/T'
  RuntimeWarning,

it does write out the out.ipynb file, though the RuntimeWarning made me think that it completely failed. This raises a few things for me:

• Should warnings be suppressed / collated?
• Should we have a --verbose / -v mode to show progress at the CLI?