See cgi.initlog():
https://github.com/python/cpython/blob/b2a91e0c9ee18b50cc86b21211c2258520a9f5d0/Lib/cgi.py#L82

```
            logfp = open(logfile, "a")
```

This feature is not documented but can be used like this.

```
import cgi
cgi.logfile="myapp.log"
cgi.log("こんにちは")
```

I want to change log file encoding to UTF-8. Although this is backward incompatible change, it unlikely break user application because it just change the logfile encoding.

UTF-8 is safer than locale encoding because UTF-8 supports all valid Unicode strings.