Attached is a patch which fixes your review comments in Lib/shutil.py, and it makes an adjustment in the wording of the documentation.

The documentation is a bit more strong in wording that the current directory is always prepended to the path whether its a provided path or the default value. I don't know that the PATHEXT mentions should go much further than saying that it's checked, and then showing what it does by example.

We always need to check the PATHEXT variable because it tells us what the accepted executable extensions are that the system will recognize. On my system, it's ".COM;.EXE;.BAT;.CMD;.VBS;.VBE;.JS;.JSE;.WSF;.WSH;.MSC;.RB;.RBW", so the command prompt allows me to type "python" and it'll search that list, search the path, and find "python.exe" at C:\Python33. It's something we need to check no matter what the `path` situation is, default or passed in.