Make shebang explicit /usr/bin/python2 where it's still there
Both Archlinux and Fedora 29 have guidelines to point explicitly at
/usr/bin/python2 where it expect python2.
Also, do not use env.
Fixes QubesOS/qubes-issues#4027
Marek Marczykowski-Górecki%!s(int64=5) %!d(string=hai) anos