bug#64939:

[Malcolm Cook]

Regarding [1] allowing emacs to recognize shebang lines containing
calls to /bin/env with options (such as -S as allowed in new core
utils [2])...

I prefer allowing the proposed "shy" regexp to match zero or more
times (using a '*' instead of '?').

To wit, I have this now in my init.el:

(setq auto-mode-interpreter-regexp
      ;; Support shbang line calling `/bin/env` with `-S` (and/or
other options).
      ;; c.f. https://debbugs.gnu.org/cgi/bugreport.cgi?bug=64939
      (purecopy "#![ \t]?\\([^ \t\n]*\
/bin/env[ \t]\\)?\\(?:-\\{1,2\\}[a-zA-Z1-9=]+[ \t]+\\)*\\([^
\t\n]+\\)"))

[1] https://debbugs.gnu.org/cgi/bugreport.cgi?bug=64939
[2] 
https://www.gnu.org/software/coreutils/manual/html_node/env-invocation.html#env-invocation

YMMV?

~ Malcolm Cook