It gives always 0 due to the print statement: 
```
$ tmux_version=1.10
luca Downloads $ python -c "ok = 1 if 1.6<=$tmux_version and $tmux_version<1.9  else 0; print ok"
0
luca Downloads $ echo $?
0
luca Downloads $ tmux_version=1.8
luca Downloads $ python -c "ok = 1 if 1.6<=$tmux_version and $tmux_version<1.9  else 0; print ok"
1
luca Downloads $ echo $?
0
```