Comment 1 for bug 1312267

Also apt-add-repository is not honouring proxy inside sudo (but both wget and apt-add-repository honours the proxy in su, when a root password is set)

gift@gift-laptop:~$ cat /etc/apt/apt.conf /etc/environment
Acquire::http::proxy "http://proxy.aims.ac.za:3128/";
Acquire::https::proxy "https://proxy.aims.ac.za:3128/";
Acquire::ftp::proxy "ftp://proxy.aims.ac.za:3128/";
PATH="/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games"
http_proxy="http://proxy.aims.ac.za:3128/"
https_proxy="https://proxy.aims.ac.za:3128/"
ftp_proxy="ftp://proxy.aims.ac.za:3128/"
gift@gift-laptop:~$ sudo apt-add-repository -y ppa:aims/aims-desktop
gpg: keyring `/tmp/tmphgyjbu9o/secring.gpg' created
gpg: keyring `/tmp/tmphgyjbu9o/pubring.gpg' created
gpg: requesting key BE796FF2 from hkp server keyserver.ubuntu.com
?: keyserver.ubuntu.com: Connection refused
gpgkeys: HTTP fetch error 7: couldn't connect: Connection refused
gpg: no valid OpenPGP data found.
gpg: Total number processed: 0
gift@gift-laptop:~$ sudo -i
root@gift-laptop:~# apt-add-repository -y ppa:aims/aims-desktop
gpg: keyring `/tmp/tmpmeup23nj/secring.gpg' created
gpg: keyring `/tmp/tmpmeup23nj/pubring.gpg' created
gpg: requesting key BE796FF2 from hkp server keyserver.ubuntu.com
?: keyserver.ubuntu.com: Connection refused
gpgkeys: HTTP fetch error 7: couldn't connect: Connection refused
gpg: no valid OpenPGP data found.
gpg: Total number processed: 0
root@gift-laptop:~# logout
gift@gift-laptop:~$ su
Password:
root@gift-laptop:/home/gift# apt-add-repository -y ppa:aims/aims-desktop
gpg: keyring `/tmp/tmp_aypocgl/secring.gpg' created
gpg: keyring `/tmp/tmp_aypocgl/pubring.gpg' created
gpg: requesting key BE796FF2 from hkp server keyserver.ubuntu.com
gpg: /tmp/tmp_aypocgl/trustdb.gpg: trustdb created
gpg: key BE796FF2: public key "Launchpad PPA for AIMS" imported
gpg: Total number processed: 1
gpg: imported: 1 (RSA: 1)
OK
root@gift-laptop:/home/gift#

Even sudo inside su does not work!

root@gift-laptop:/home/gift# sudo apt-add-repository -y ppa:aims/aims-desktop
gpg: keyring `/tmp/tmp9kcefxji/secring.gpg' created
gpg: keyring `/tmp/tmp9kcefxji/pubring.gpg' created
gpg: requesting key BE796FF2 from hkp server keyserver.ubuntu.com
?: keyserver.ubuntu.com: Connection refused
gpgkeys: HTTP fetch error 7: couldn't connect: Connection refused
gpg: no valid OpenPGP data found.
gpg: Total number processed: 0
root@gift-laptop:/home/gift#

sudo is a very common and recommended way to add a repository.