Debug packages not found for Okular

KDE PDF viewer Okular had a segmentation fault on Byzantium, and a dialog I opened from a notification icon suggested installing debug packages in order to get and report a useful backtrace. So, after some web browsing in and I appended the following line to etc/apt/sources.list:

deb byzantium-debug main

but I still can’t find debug packages for Okular and its dependencies. Have I missed something? Should I look for debug packages in Debian testing repositories?