Setting a new host removes line comments from existing hosts

Given a hosts file like:
```
127.0.0.1 localhost
10.0.0.100 otherhost # some comment
```

Adding a new configuration with `hostile set 127.0.0.1 newhost` adds the new host but removes the line comment from the existing entry, leaving
```
127.0.0.1 localhost
10.0.0.100 otherhost
127.0.0.1 newhost
```

I would expect this tool to leave existing line comments intact. I have other tooling which depends on their presence.