Error when modifying firewall interface attributes on a parent firewall interface with sub-interfaces

def config_comment(fw_obj):
    x = ['ethernet1/1']

    try:
        EthernetInterface.refreshall(fw_obj)
        AggregateInterface.refreshall(fw_obj)
    except PanDeviceError as e:
        print(e.message)

    for interface_name in x:
        if 'ae' in interface_name:
            try:
                target_int = fw_obj.find(interface_name, AggregateInterface)
            except PanDeviceError as e:
                print(e.message)         
        elif 'ethernet' in interface_name:
            try:
                target_int = fw_obj.find(interface_name, EthernetInterface)
            except PanDeviceError as e:
                print(e.message) 
        else:
            print('Invalid interface {0}'.format(interface_name))

        target_int.comment = 'test comment'

        target_int.apply()

Error:

Traceback (most recent call last):
  File "/home/admin/venvs/auto_venv_py3.6/lib64/python3.6/site-packages/pandevice/base.py", line 3447, in method
    super_method(self, *args, **kwargs)
  File "/home/admin/venvs/auto_venv_py3.6/lib64/python3.6/site-packages/pan/xapi.py", line 741, in set
    self.__type_config('set', query, extra_qs)
  File "/home/admin/venvs/auto_venv_py3.6/lib64/python3.6/site-packages/pan/xapi.py", line 805, in __type_config
    raise PanXapiError(self.status_detail)
pan.xapi.PanXapiError:  interface 'ethernet1/1.2' is already in use

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "enable_lldp.py", line 154, in <module>
    main()
  File "enable_lldp.py", line 151, in main
    config_lldp(firewall, lldp_ints)
  File "enable_lldp.py", line 122, in config_lldp
    target_int.apply()
  File "/home/admin/venvs/auto_venv_py3.6/lib64/python3.6/site-packages/pandevice/base.py", line 3001, in apply
    super(VsysOperations, self).apply()
  File "/home/admin/venvs/auto_venv_py3.6/lib64/python3.6/site-packages/pandevice/base.py", line 561, in apply
    child._check_child_methods("apply")
  File "/home/admin/venvs/auto_venv_py3.6/lib64/python3.6/site-packages/pandevice/base.py", line 518, in _check_child_methods
    getattr(self, "child_"+method)()
  File "/home/admin/venvs/auto_venv_py3.6/lib64/python3.6/site-packages/pandevice/base.py", line 3012, in child_apply
    return self._create_apply_child()
  File "/home/admin/venvs/auto_venv_py3.6/lib64/python3.6/site-packages/pandevice/base.py", line 3019, in _create_apply_child
    self.create_import('vsys1')
  File "/home/admin/venvs/auto_venv_py3.6/lib64/python3.6/site-packages/pandevice/base.py", line 3050, in create_import
    device.active().xapi.set(xpath, element, retry_on_peer=True)
  File "/home/admin/venvs/auto_venv_py3.6/lib64/python3.6/site-packages/pandevice/base.py", line 3464, in method
    raise the_exception
pandevice.errors.PanDeviceXapiError:  interface 'ethernet1/1.2' is already in use

Python Module Versions:
pan-python 0.15.0
pandevice 0.11.1

Start with the apply flow shown in pandevice/base.py, especially child_apply and create_import, then inspect pan/xapi.py where set raises the interface-in-use error. Reproduce the supplied EthernetInterface example with a parent interface that has sub-interfaces; done means modifying the parent interface attributes without the reported ethernet1/1.2 conflict.