Example:
pathfix.py -i /usr/bin/python ./directory --> would change the shebang of
every script in this directory recursively to #! /usr/bin/python. That's handy but if you would have script like this: #! /usr/bin/env -flags and
wanted to keep the flags.
You would need to run again pathfix: pathfix.py -i '/usr/bin/python -flags' ./directory. That is not that bad for one script but with increasing number of scripts, differences of flags between the scripts it gets harder.