For future reference, use ~ or null in place of None to make PyYAML interpret it as a literal None instead of the string "None":
mount_default_fields: [~, ~, 'auto', 'defaults,nofail', '0', '2']
For future reference, use ~ or null in place of None to make PyYAML interpret it as a literal None instead of the string "None":
mount_default_ fields: [~, ~, 'auto', 'defaults,nofail', '0', '2']