IP address broken with --net=host

```bash
docker run --rm --net=host fnndsc/pfurl --http 127.0.0.1:5010/api/v1/cmd
Traceback (most recent call last):
File "/usr/local/bin/pfurl", line 23, in
str_defIP = [l for l in ([ip for ip in socket.gethostbyname_ex(socket.gethostname())[2] if not ip.startswith("127.")][:1], [[(s.connect(('8.8.8.8', 53)), s.getsockname()[0], s.close()) for s in [socket.socket(socket.AF_INET, socket.SOCK_DGRAM)]][0][1]]) if l][0][0]
socket.gaierror: [Errno -2] Name or service not known
```

Reproduce the failure with the documented `docker run --rm --net=host fnndsc/pfurl --http 127.0.0.1:5010/api/v1/cmd` command and inspect the `/usr/local/bin/pfurl` entry point, especially the address-detection expression shown in the traceback. Done means the command no longer raises this `socket.gaierror` when run with host networking.

Written by the indexing model from the issue text.