Bigint issue with fleece in Claudwatch

[muzafferpey]

Hi all,
I have a SessionId attribute which is stored as an integer. When I log it as an integer in my Lambda function using fleece, it gets rounded in a weird way (something like divided by 1000, rounded and multiplied by 1000). See sample code lines and Cloudwatch logs:

Sample code:
session_id_str = str(record_dict["data"]["acctsessionid"])
session_id_int = int(session_id_str)
session_id_int_str = str(session_id_int)

print(f"session_id_str: {session_id_str}")
print(f"session_id_int: {session_id_int}")
print(f"session_id_int_str: {session_id_int_str}")

cloudwatch_logger.info(
session_id_str=session_id_str,
session_id_int=session_id_int,
session_id_int_str=session_id_int_str,
)

Cloudwatch logs (note that the printed one is correct):
session_id_str: 14054155204119893643
session_id_int: 14054155204119893643
session_id_int_str: 14054155204119893643

{ "level": "info", "logger": "CloudWatch", "session_id_int": 14054155204119894000, "session_id_int_str": "14054155204119893643", "session_id_str": "14054155204119893643", "timestamp": "2019-06-12T15:04:35.345307Z" }

so:
14054155204119893643 is rounded to 14054155204119894000

Environment:
appdirs==1.4.3
attrs==19.1.0
black==19.3b0
boto3==1.9.164
botocore==1.12.164
certifi==2019.3.9
chardet==3.0.4
Click==7.0
docutils==0.14
fleece==0.18.4
idna==2.8
jmespath==0.9.4
protobuf==3.8.0
python-dateutil==2.8.0
requests==2.22.0
s3transfer==0.2.1
six==1.12.0
structlog==19.1.0
toml==0.10.0
urllib3==1.25.3
wrapt==1.11.1

Lambda runtime: Python3.6 in us-east-1 region.

Thanks in advance!