Do not add python executable to executable scripts when reloading
Do not add python executable to executable scripts when reloading

Sometimes, the file in `sys.argv[0]` may use an interpreter
other than python.  For example; NixOs replaces `sys.argv[0]` to a
wrapper shell script which changes the environment variables before
running the main entrypoint.

Currently, the reloader assumes that all scripts need the python
interpreter appended their command line.  This patch changes that to
check if the script is set as executable, and does not use the
python command if it is.

fkazimierczak/werkzeug,pallets/werkzeug,pallets/werkzeug,mitsuhiko/werkzeug,fkazimierczak/werkzeug,mitsuhiko/werkzeug,fkazimierczak/werkzeug,pallets/werkzeug