When listening to channels, `curl_options_common` is ignored, which may lead to confusing errors

[onnozweers]

This is the standard config in ada/etc/ada.conf:

# Adding --ipv4 to the default curl options.
# We're running on an IPv4 only system, but curl still tries IPv6.
# When the API is down, curl will say "Network is unreachable";
# But curl --ipv4 will say: "Connection refused" which is more clear.

curl_options_common=(
                      -H "accept: application/json"
                      --fail --silent --show-error
                      --ipv4
                    )

It turns out, that when listening to a channel, curl_options_common is not used, and then the --ipv4 option is skipped, which may lead to an error (if IPv6 is not properly supported).

I think it's this piece of code:

    curl "${curl_authorization[@]}" \
         "${curl_options_stream[@]}" \
         -X GET "$channel" \
         "${last_event_id_header[@]}"

curl_options_common is not in here by design, because listening to channels required some different curl options than most other API operations.

Options:

• Add curl_options_stream to ada/etc/ada.conf with an --ipv4 option. This is easy.
• Make sure curl_options_common is applied to ALL operations. We'd have to move some curl arguments around to make this work.