Stop assuming that /usr/bin/python3 exists
python3 is in /usr/local/bin on my system, so I see:
$ scripts/maint/practracker/practracker.py
-bash: scripts/maint/practracker/practracker.py: /usr/bin/python3: bad interpreter: No such file or directorypython3 is in /usr/local/bin on my system, so I see:
$ scripts/maint/practracker/practracker.py
-bash: scripts/maint/practracker/practracker.py: /usr/bin/python3: bad interpreter: No such file or directory