Bug#1127561: tumbler: thumbnailing broken with gdk-pixbuf+glycin

[Jeremy Bícha]

Control: reassign -1 src:tumbler 4.20.0-1

Yves-Alexis, could you cherry-pick the tumbler fix for this issue? See
the previous comments at
https://bugs.debian.org/1127561

Thank you,
Jeremy Bícha