Comment 5 for bug 1132892

@ Ian
yes and no, we also want to avoid gaining an explicit dependency on each python3.X package at build-time, when later python3.X+1 can become default thus requiring an useless no-change upload to fix up the dependencies.

This is more for the name of the script that will have /usr/bin/python3 shebang and that should be stable (e.g. point to default python3 version regardless of which exact version that symlink points to)