Since in the main (ubuntu) menu System > Network Proxy, you have an "apply system wide", this "http_proxy" variable should be taken care of somehow...
Either
a/ by passing it through sudo
b/ the menu configuration add it somewhere somehow so that sudo get initialized with the "global official variable" (if a sudo.initial_env file would have existed, should be placed there).
Since in the main (ubuntu) menu System > Network Proxy, you have an "apply system wide", this "http_proxy" variable should be taken care of somehow...
Either
a/ by passing it through sudo
b/ the menu configuration add it somewhere somehow so that sudo get initialized with the "global official variable" (if a sudo.initial_env file would have existed, should be placed there).
solution b is more security-proof.