image zooming interpolation

[Dennis <dennis nezic utoronto ca>]

I'm not sure what changed on my system =( .. but suddenly the Hyper
zooming feature in gqview, and the Cubic interpolation for zooming in
gimp do not seem to be working.

I upgraded a whole bunch of packages, but the problem persists.

gimp 2.0.4
gqview 1.5.4
glib 2.4.7
gdk-pixbuf 0.22.0-r3

Any idea what else might be preventing interpolation from occuring?
Zooming works, but no interpolation.