Actually I just think they should fix the bug. apt-add-repository is a very useful standard command and in a Debian fork that want to be called a major one all the widely used Debian tools should work.

And it is simple just adding the correct lsb-release would fix the problem.

I could suggest, like in many places i read, that it can be fixed by adding the file /etc/lsb-release with the following text in it:

DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=12.04
DISTRIB_CODENAME=precise
DISTRIB_DESCRIPTION="Ubuntu 12.04 LTS"

But I would not call this a fix, but an ugly patch, since the file should have the right Kali info instead of Ubuntu one... but it is not up to me to decide which those are.

and even then, if i did put in the file the following correct info, it would not work like the above incorrect info.

DISTRIB_ID=Debian
DISTRIB_RELEASE="Kali Linux 1.0"
DISTRIB_CODENAME=n/a
DISTRIB_DESCRIPTION="Debian GNU/Linux Kali Linux 1.0"

so it is something that someone else has to fix or at least address us on how to fix it properly
knock knock... Hello Kali devs...mantainers...