qemu-img: GLib: g_hash_table_foreach_remove: assertion 'hash_table != NULL' failed
Description of problem:
Mixing driver=https with an http URL gives this assert fail in glib2:

```
$ ~/d/qemu/build/qemu-img convert -p -W -f qcow2 'json:{ "file.readahead": 67108864, "file.driver": "https", "file.url": "http://web/tmp/jammy-server-cloudimg-amd64.qcow2", "file.timeout":2000 }' -O raw jammy-server-cloudimg-amd64.img.raw 
qemu-img: GLib: g_hash_table_foreach_remove: assertion 'hash_table != NULL' failed
qemu-img: GLib: g_hash_table_destroy: assertion 'hash_table != NULL' failed
qemu-img: Could not open 'json:{ "file.readahead": 67108864, "file.driver": "https", "file.url": "http://web/tmp/jammy-server-cloudimg-amd64.qcow2", "file.timeout":2000 }': https curl driver cannot handle the URL 'http://oirase.annexia.org/tmp/jammy-server-cloudimg-amd64.qcow2' (does not start with 'https://')
```

(It seems to be a warning rather than a crash)
Steps to reproduce:
1. Run the command above.