Single file version doesn't work when only python3 is installed

[grzanka]

root@1ede2f6a2773:/# wget https://github.com/DataMedSci/mcpartools/releases/download/v0.1.4/generatemc.pyz -O generatemc
(...)
2016-09-20 11:30:34 (156 KB/s) - 'generatemc' saved [37191/37191]

root@1ede2f6a2773:/# chmod ugo+x generatemc
root@1ede2f6a2773:/# ./generatemc --version
/usr/bin/env: 'python': No such file or directory
root@1ede2f6a2773:/# python3 -V
Python 3.5.2
root@1ede2f6a2773:/# python -V 
bash: python: command not found

Tested on Ubuntu 16.04