I'm in favor of this.

I especially want this with the self-name-checking that Eryk mentioned, and even more if each installed Python adds its own symlink to `py.exe` with its own version (i.e. the Python 3.9 installer adds `python3.9.exe -> py.exe`).  I'm good with the base change even without these enhancements, though.

(Maybe at some point in the future we can do something crazy like have the launcher just load the appropriate python3X.dll and run as the python process itself, but that is its own can of worms and should not stand in the way of this improvement :))