Avoid Recursive Shells

what

• Export SHELL to match the desired shell, rather than the current sudosh shell
• Do not use -s as it causes an unnecessary subshell
• Emulate more closely the behavior of the desired shell (which is why we dropped the --)

why

• When SHELL was set to the current sudosh wrapper shell, it would cause infinite loops for non-login shells (E.g. where a command was passed via ssh)
• Better compatibility with system login shells