Structured conf with parent + default-factory field does not have correct initial value (distinct from #817)

[rsokl]

Running against omegaconf hash f362b5c (latest commit on master as of posting this)

This is very similar to #817 , but the issue arises whenever the parent's attribute is anything other than MISSING

from dataclasses import field, dataclass
from typing import Any

from omegaconf import OmegaConf

@dataclass
class BasicConf:
    setup: Any = 1


@dataclass
class Config(BasicConf):
    setup: Any = field(default_factory=lambda: list(["hi"]))

>>> Config.setup
1
>>> Config().setup
['hi']
>>> OmegaConf.create(Config)
{'setup': 1}

I would expect OmegaConf.create to create the config based off of the dataclass-instance, not the dataclass-object. This led to a hard-to-find bug downstream in a Hydra application, where a mutable default value was silently being ignored.

[Jasha10]

Awesome, thanks for reporting this!