From O_MAYEXEC to trusted_for()

Well the problem is not with -s in general, but using it when you could pass the file name instead. If you load the script contents into memory with `cat` and then pass it as an argument to Python with -s, Python can't check the original file with `trusted_for`. It either has to assume the script is trusted, disable -s or sh/cat needs to check the permissions before passing the data to Python. I suppose there is the same issue with passing data on stdio, which is mentioned in the article.

Also, on a partially related note, there was some buffer overflow or "stack smashing" attack involving large command lines and now the linux command line length is much more limited to prevent that, so you probably don't want to use `-s` in shell scripts unless it is a string of known length generated in the script or static.

BTW "most people" includes myself when I'm in a less trusted state.