ERROR:cot:No namespace prefix on _attrib_{http://schemas.dmtf.org/ovf/envelope/1}required??

[glennmatthews]

When running cot edit-hardware under Python 3, the following error message is reported, although the file is edited correctly:

ERROR:cot:No namespace prefix on _attrib_{http://schemas.dmtf.org/ovf/envelope/1}required??

Adding -v shows some context:

ERROR:cot:No namespace prefix on _attrib_{http://schemas.dmtf.org/ovf/envelope/1}required??
WARNING:cot:Profile 1CPU-3GB already exists under OVFItem:  ElementName
    Serial 2             : {'<default>'}
  ResourceType
    21                   : {'<default>'}
  _attrib_{http://schemas.dmtf.org/ovf/envelope/1}required
    false                : {'<default>'}
  Description
    Auxiliary Port       : {'<default>'}
  InstanceID
    9                    : {'<default>'}
  AutomaticAllocation
    true                 : {'<default>'}
!