[Qgis-user] What's python-software-properties necessary for?

[Anita Graser]

Hi,

I've been going through our installation instructions on the wiki:
http://hub.qgis.org/projects/quantum-gis/wiki/Download#262-With-updated-dependencies

There is one thing I don't quite understand: Only if I want to install
QGIS with updated dependencies, the instructions tell me to install
python-software-properties:

sudo apt-get install python-software-properties

It's not mentioned anywhere else. What's this package good for? Is it
necessary? Why does it seem to be only necessary for installing the
QGIS release from ubuntugis-unstable but not with any other source?

Thanks and best wishes,
Anita