@Brian I have fixed the bug concerning the "SystemError: cannot determine default mirror", apport made the wrong assumption that all repo lines start with http://.
I was able to get the sandbox working by modifying /usr/lib/python3/dist-packages/apt/cache.py to not raise an exception in case of untrusted packages, but it is a serious bug that it cannot verify packages, I hope you can help there, I am not able to fix this by myself.
@Brian I have fixed the bug concerning the "SystemError: cannot determine default mirror", apport made the wrong assumption that all repo lines start with http://.
I was able to get the sandbox working by modifying /usr/lib/ python3/ dist-packages/ apt/cache. py to not raise an exception in case of untrusted packages, but it is a serious bug that it cannot verify packages, I hope you can help there, I am not able to fix this by myself.