core: Yamaha RXV Zone_2 not working anymore after Update to 0.78.0

Home Assistant release with the issue: 0.78.0

Last working Home Assistant release (if known): 0.77.3

Operating environment (Hass.io/Docker/Windows/etc.): gentoo linux amd64 current stable profile 17.0 nomultilib (very thin install)

except the follwing python updates required by home-assistant:

• dev-python/astral-1.6.1
• dev-python/attrs-18.2.0
• dev-python/cryptography-2.3.1
• dev-python/pyjwt-1.6.4
• dev-python/voluptuous-0.11.5
• dev-python/pyyaml-3.13
• dev-python/aiohttp-cors-0.6.0
• dev-python/bcrypt-3.1.4
• dev-python/idna-ssl-1.0.1
• dev-python/async_timeout-3.0.0

with the 0.78.0 update

• dev-python/voluptuous-serialize-2.0.0
• dev-python/colorlog-3.1.4 were newly installed and
• dev-python/aiohttp-3.4.0 has been updated.

Component/platform: Yamaha RXV-679, platform: yamaha (worked great up to now), also tried yamaha_musiccast without success. All Yamahas are on wired network, Firmware is 2.10, will also try current FW 2.58 tomorrow.

Description of problem: Since Upgrade to 0.78.0 Zone_2 does not show up anymore, lots of tracebacks.

Problem-relevant configuration.yaml entries and (fill out even if it seems unimportant): removed source_ignore and source_names for testing:

- platform: yamaha
  name: RXV_Werkstatt
  host: rxv679-werkstatt.in.xxx.net
  zone_ignore:
    - "Zone_2"
  zone_names:
    Main_Zone: "Werkstatt"

- platform: yamaha
  name: RXV_Wohnzimmer
  host: rxv679-wohnen.in.xxx.net
  zone_names:
    Zone_2: "TerasseR"
    Main_Zone: "Wohnzimmer"

- platform: yamaha
  name: RXV_Kitchen
  host: rxv679-kueche.in.xxx.net
  zone_names:
    Main_Zone: "Kueche"
    Zone_2: "BadezimmerEG"

Traceback (if applicable):

2018-09-19 22:55:46 ERROR (SyncWorker_35) [rxv] Invalid XML returned for request <YAMAHA_AV cmd="GET"><Zone_2><Surround><Program_Sel><Current>GetParam</Current></Program_Sel></Surround></Zone_2></YAMAHA_AV>: b''
Traceback (most recent call last):
  File "/etc/homeassistant/deps/lib64/python3.6/site-packages/rxv/rxv.py", line 139, in _request
    response = ET.XML(res.content)  # releases connection to the pool
  File "/usr/lib64/python3.6/xml/etree/ElementTree.py", line 1315, in XML
    return parser.close()
  File "<string>", line None
xml.etree.ElementTree.ParseError: no element found: line 1, column 0
2018-09-19 22:55:46 ERROR (MainThread) [homeassistant.helpers.entity] Update for media_player.rxv_kitchen_kzone2 fails
Traceback (most recent call last):
  File "/usr/lib64/python3.6/site-packages/homeassistant/helpers/entity.py", line 224, in async_update_ha_state
    yield from self.async_device_update()
  File "/usr/lib64/python3.6/site-packages/homeassistant/helpers/entity.py", line 353, in async_device_update
    yield from self.hass.async_add_job(self.update)
  File "/usr/lib64/python3.6/concurrent/futures/thread.py", line 56, in run
    result = self.fn(*self.args, **self.kwargs)
  File "/usr/lib64/python3.6/site-packages/homeassistant/components/media_player/yamaha.py", line 187, in update
    self._sound_mode = self.receiver.surround_program
  File "/etc/homeassistant/deps/lib64/python3.6/site-packages/rxv/rxv.py", line 296, in surround_program
    response = self._request('GET', request_text)
  File "/etc/homeassistant/deps/lib64/python3.6/site-packages/rxv/rxv.py", line 139, in _request
    response = ET.XML(res.content)  # releases connection to the pool
  File "/usr/lib64/python3.6/xml/etree/ElementTree.py", line 1315, in XML
    return parser.close()
  File "<string>", line None
xml.etree.ElementTree.ParseError: no element found: line 1, column 0

Error shows up every 11 seconds. Additional information:

zone_ignore:
    - "Zone_2"

lets errors & tracebacks vanish. Thanks a lot for your great work!