Unable to add ppa behind proxy

While trying to add softwares from sources other than the central debian repository, we may have to add a PPA (Personal Package Archive), so that the software(apt or aptitude) which installs other softwares fetches packages for us from the new location.

The default or normal method to add a PPA via command line is as follows:

sudo add-apt-repository ppa:something

However, if you are behind a proxy, you may not be able to add this way and when you try to do something like this:

sudo add-apt-repository ppa:gnome3-team/gnome3

you may get an error like this:

Cannot access PPA (https://launchpad.net/api/1.0/~gnome3-team/+archive/gnome3) to get PPA information, please check your internet connection.

This may happen even if you have added your proxy using System Settings -> Network -> Network proxy or in /etc/apt/apt.conf or even in /home/$USER/.bashrc. This is because the sudo user is not aware of the proxy set in the places above. This tutorial explains how to make this work to add a PPA the terminal way.

So lets get started. Please note that all commands and text hereon are case-senstive, take care not to make any typos hereon, to avoid messing up your system):

• Open a terminal using Ctrl + Alt + t
• Type
  export http_proxy="http://username:password@your proxy":"port"
export https_proxy="https://username:password@your proxy":"port"
  Remember to replace "username" by your username and "password" by your password, if applicable, "your proxy" by your proxy address like 10.1.101.150 or proxy.college and "port" by something like 3128.
• Now we have two methods to export these parameter to "sudo" user:

Method 1:

• Type sudo visudo
• Add Defaults env_keep="https_proxy" to the end of the file. (Note that Defaults has a capital "d")
• Type Ctrl + x and y to save and exit.

Method 2:

• Whenever you use sudo command, export the environment variables of the user you are currently using. To do this, when you use sudo, use sudo -E

You are now ready to add PPA using the terminal. Please let me know, via comments, if you face any issues while doing this.
Source: The bug filed regarding this at launchpad.