OmegaConf.to_yaml does not convert Enum DictConfig keys to string

[Jasha10]

from enum import Enum
from omegaconf import OmegaConf

class Color(Enum):
    RED = 1
    BLUE = 2

conf = OmegaConf.create({Color.RED: Color.BLUE})

print(OmegaConf.to_yaml(conf))

Outputs:

? !!python/object/apply:__main__.Color
- 1
: BLUE

Expected output:

RED: BLUE

Note that the DictConfig value Color.BLUE is converted to a string, but the key Color.RED is not.