add python prefix for python scripts when there is no .py extension (#…

…1589)

* add python prefix for python script when there is no .py extension

* consolidate and minimize change to existing code

* update comment

* revert unnecessary change from sys.platform to os.name

tools/roslaunch/src/roslaunch/node_args.py

@@ -260,7 +260,10 @@ def create_local_process_args(node, machine, env=None):
     if not cmd:
         raise NodeParamsException("Cannot locate node of type [%s] in package [%s]"%(node.type, node.package))
     cmd = [cmd]
-    if sys.platform in ['win32']:
-        if os.path.splitext(cmd[0])[1] == '.py':
-            cmd = ['python'] + cmd
+
+    # Python scripts in ROS tend to omit .py extension since they could become executable
+    # by adding a shebang line (#!/usr/bin/env python) in Linux environments
+    # special handle this case by executing the script with the Python executable in Windows environment
+    if sys.platform in ['win32'] and os.path.splitext(cmd[0])[1].lower() in ['.py', '']:
+        cmd = ['python'] + cmd
     return _launch_prefix_args(node) + cmd + args