apt-key calls wget without proxy environment variable

When running as a regular user the command 'sudo update-manager -d', sudo strips the environment of the http_proxy variable which is needed for "apt-key netupdate" to run wget and update Ubuntu keyring.

Even setting the proxy environment variables from /etc/environment or modifying the APT proxy settings via Acquire::http { Proxy ... } as apt-key calls wget to fetch the keyring instead of using APT internals.