Comment 0 for bug 1615780

When apply_net fails, the user both a fail message and a success message.. a bit confusing.

root@x1:~# curtin apply_net -t target -c bad.yaml
Applying network configuration
failed to apply network config
Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/curtin/commands/apply_net.py", line 78, in apply_net_main
    network_config=state['network_config'])
  File "/usr/lib/python3/dist-packages/curtin/commands/apply_net.py", line 44, in apply_net
    ns = net.parse_net_config(network_config)
  File "/usr/lib/python3/dist-packages/curtin/net/__init__.py", line 283, in parse_net_config
    net_config = config.load_config(path)
  File "/usr/lib/python3/dist-packages/curtin/config.py", line 117, in load_config
    return yaml.safe_load(content)
  File "/usr/lib/python3/dist-packages/yaml/__init__.py", line 94, in safe_load
    return load(stream, SafeLoader)
  File "/usr/lib/python3/dist-packages/yaml/__init__.py", line 72, in load
    return loader.get_single_data()
  File "/usr/lib/python3/dist-packages/yaml/constructor.py", line 35, in get_single_data
    node = self.get_single_node()
  File "/usr/lib/python3/dist-packages/yaml/composer.py", line 36, in get_single_node
    document = self.compose_document()
  File "/usr/lib/python3/dist-packages/yaml/composer.py", line 55, in compose_document
    node = self.compose_node(None, None)
  File "/usr/lib/python3/dist-packages/yaml/composer.py", line 84, in compose_node
    node = self.compose_mapping_node(anchor)
  File "/usr/lib/python3/dist-packages/yaml/composer.py", line 133, in compose_mapping_node
    item_value = self.compose_node(node, item_key)
  File "/usr/lib/python3/dist-packages/yaml/composer.py", line 84, in compose_node
    node = self.compose_mapping_node(anchor)
  File "/usr/lib/python3/dist-packages/yaml/composer.py", line 127, in compose_mapping_node
    while not self.check_event(MappingEndEvent):
  File "/usr/lib/python3/dist-packages/yaml/parser.py", line 98, in check_event
    self.current_event = self.state()
  File "/usr/lib/python3/dist-packages/yaml/parser.py", line 428, in parse_block_mapping_key
    if self.check_token(KeyToken):
  File "/usr/lib/python3/dist-packages/yaml/scanner.py", line 116, in check_token
    self.fetch_more_tokens()
  File "/usr/lib/python3/dist-packages/yaml/scanner.py", line 257, in fetch_more_tokens
    self.get_mark())
yaml.scanner.ScannerError: while scanning for the next token
found character '\t' that cannot start any token
  in "<unicode string>", line 4, column 5:
              config:
        ^
Applied network configuration successfully

Note the emitting of messages

"failed to apply network config"
AND
"Applied network configuration successfully"

Really a minor issue.