[2.6] Machine doesn't transition to deployed state with bonds/bridges on pxe interface

The real issue it seems is that the netplan we are sending in 2.6 is incorrect.

[ 3.336953] cloud-init[376]: Cloud-init v. 18.4-0ubuntu1~18.04.1 running 'init-local' at Thu, 28 Feb 2019 19:18:30 +0000. Up 3.17 seconds.
[ 3.338380] cloud-init[376]: 2019-02-28 19:18:30,921 - handlers.py[WARNING]: failed posting event: start: init-local/check-cache: attempting to read from cache [trust]
[ 3.345315] cloud-init[376]: 2019-02-28 19:18:30,930 - handlers.py[WARNING]: failed posting event: finish: init-local/check-cache: SUCCESS: no cache found
[ OK ] Listening on Load/Save RF Kill Switch Status /dev/rfkill Watch.
[ 3.653366] cloud-init[376]: 2019-02-28 19:18:31,241 - util.py[WARNING]: failed stage init-local
[ 3.672269] cloud-init[376]: failed run of stage init-local
[ 3.673103] cloud-init[376]: ------------------------------------------------------------
[ 3.674119] cloud-init[376]: Traceback (most recent call last):
[ 3.674956] cloud-init[376]: File "/usr/lib/python3/dist-packages/cloudinit/cmd/main.py", line 323, in main_init
[ 3.680227] cloud-init[376]: init.fetch(existing=existing)
[ 3.683134] cloud-init[376]: File "/usr/lib/python3/dist-packages/cloudinit/stages.py", line 351, in fetch
[ 3.689217] cloud-init[376]: return self._get_data_source(existing=existing)
[ 3.692494] cloud-init[376]: File "/usr/lib/python3/dist-packages/cloudinit/stages.py", line 261, in _get_data_source
[ 3.696974] cloud-init[376]: pkg_list, self.reporter)
[ 3.700725] cloud-init[376]: File "/usr/lib/python3/dist-packages/cloudinit/sources/__init__.py", line 677, in find_source
[ 3.708092] cloud-init[376]: raise DataSourceNotFoundException(msg)
[ 3.713043] cloud-init[376]: cloudinit.sources.DataSourceNotFoundException: Did not find any data source, searched classes: ()
[ 3.715414] cloud-init[376]: During handling of the above exception, another exception occurred:
[ 3.724161] cloud-init[376]: Traceback (most recent call last):
[ 3.725516] cloud-init[376]: File "/usr/lib/python3/dist-packages/cloudinit/cmd/main.py", line 658, in status_wrapper
[ 3.728192] cloud-init[376]: ret = functor(name, args)
[ 3.728874] cloud-init[376]: File "/usr/lib/python3/dist-packages/cloudinit/cmd/main.py", line 341, in main_init
[ 3.736792] cloud-init[376]: init.apply_network_config(bring_up=not args.local)
[ 3.740703] cloud-init[376]: File "/usr/lib/python3/dist-packages/cloudinit/stages.py", line 671, in apply_network_config
[ 3.742942] cloud-init[376]: return self.distro.apply_network_config(netcfg, bring_up=bring_up)
[ 3.751857] cloud-init[376]: File "/usr/lib/python3/dist-packages/cloudinit/distros/__init__.py", line 178, in apply_network_config
[ 3.754374] cloud-init[376]: dev_names = self._write_network_config(netconfig)
[ 3.755391] cloud-init[376]: File "/usr/lib/python3/dist-packages/cloudinit/distros/debian.py", line 114, in _write_network_config
[ 3.768212] cloud-init[376]: return self._supported_write_network_config(netconfig)
[ 3.771124] cloud-init[376]: File "/usr/lib/python3/dist-packages/cloudinit/distros/__init__.py", line 93, in _su...

It seems that the order of the keys in the netplan YAML matter, which to me is incorrect and it should not matter.

https://bugs.launchpad.net/netplan/+bug/1818147

To fix this we will need to look into how yaml.dumps determines the order to render the YAML. We might need to some how override the default behavior so netplan is happy with the YAML.