python-rrd doesn't know --left-axis-formatter

Hello there,

I'm using python-rrdtool 1.4.8 (and rrdtool 1.4.8) on a raspberry Pi. It 
has been installed via apt-get from mirrordirector.raspbian.org

When I try to use --left-axis-formatter in a rrd-graph, I encounter: 
rrdtool.error: unknown option '--left-axis-formatter'

And same thing if I try directly in bash.

Do I need an earlier version ? And more: why the last stable version is 
not in debian nor raspbian repositories ?

Regards,
CrazyCat