Hello nbi, I am not involved in packaging gimp, but this might be related to the debian-multimedia packages you have installed:
> ii libbabl-0.1-0 1:0.1.74-dmo1 > ii libgegl-0.4-0 1:0.4.16-dmo1 Is this error also visible when using these packages from the debian testing repository? (Or is there at least for these two packages an update in the debian-multimedia repo?) Kind regards, Bernhard