Fix Hacking H304 Warnings

And also enable it permanently.

Change-Id: Iae319ecaee86049bc25330e25c4f672e3b158851
a minor fix to volume.py

There seems a typo with the exception name and the comment.

Change-Id: I5c0abe48c81a69e4b879b080236899031bb40e97
Merge "a minor fix to volume.py"
Merge "Fix Hacking H304 Warnings"