The builds of basemap and matplotlib on powerpcspe and sh4 seem to have been interrupted by a circular dependency, now fixed in matplotlib 2.0.0-1 (bug#849943). These packages are holding up the build of vtk6 on these arches.
The buildd status for these packages are still showing as "BD-Uninstallable". Do they need to be given back manually? gb matplotlib_2.0.0+dfsg1-2 . powerpcspe sh4 gb basemap_1.0.7+dfsg-4 . powerpcspe sh4 Cheers, Drew