DNS lookup before fork causes lookup failure after fork on OSX

I'm running into a really specific and weird bug on OSX.

Reproduction instructions

Use OSX. I am using 10.15.4 right now; I don't know if the specific version matters.

Install daemonize 2.5.0.

Run this script:

#!/usr/bin/env python3
import socket
from daemonize import Daemonize

def run():
    print(socket.gethostbyname('google.com'))

if __name__ == '__main__':
    print(socket.gethostbyname('google.com'))
    daemon = Daemonize(app="monitor_script", pid="./test.pid", action=run, foreground=False)
    daemon.start()

Symptoms of bug

Before forking, the Python program can successfully do a DNS lookup.

The following message appears in Console.app under Log Reports > system.log:

Jul 31 14:22:24 Nicks-MacBook-Pro monitor_script: Starting daemon.
Jul 31 14:22:24 Nicks-MacBook-Pro monitor_script: Traceback (most recent call last):
Jul 31 14:22:24 Nicks-MacBook-Pro monitor_script:   File "/Users/nick/.pyenv/versions/3.6.10/lib/python3.6/site-packages/daemonize.py", line 248, in start
Jul 31 14:22:24 Nicks-MacBook-Pro monitor_script:     self.action(*privileged_action_result)
Jul 31 14:22:24 Nicks-MacBook-Pro monitor_script:   File "test.py", line 7, in run
Jul 31 14:22:24 Nicks-MacBook-Pro monitor_script:     print(socket.gethostbyname('google.com'))
Jul 31 14:22:24 Nicks-MacBook-Pro monitor_script: socket.gaierror: [Errno 8] nodename nor servname provided, or not known
Jul 31 14:22:24 Nicks-MacBook-Pro monitor_script: Stopping daemon.

Variations tried

I have run the reproduction script on Linux, and it can successfully resolve DNS before and after forking. (This is why I marked this as an OSX-specific bug.)

I have run the reproduction script without the first DNS lookup. This works.

I have run the reproduction script with foreground=True. This works.

I've tried putting a sleep between the two DNS lookups. This doesn't help.

Workaround

Don't do DNS lookups before forking.

thesharp / daemonize