tramp-shell-open doesn't work with rc shell

[Jeff Mickey]

In tramp-open-shell, there is this line:

(tramp-send-command 
      vec (format 
	    (concat "exec env TERM='%s' INSIDE_EMACS='%s,tramp:%s' 
	     " "ENV=%s %s PROMPT_COMMAND='' PS1=%s PS2='' PS3='' 
	     %s %s") 
           tramp-terminal-type emacs-version tramp-version  ; 
           INSIDE_EMACS (or (getenv-internal "ENV" 
           tramp-remote-process-environment) "") 

And this breaks rc shells, as the '=' sign appearing after an 
initial command is an invalid syntax in this shell. The shell may 
support this syntax in a while, but it does not currently and has 
not since it was made.

I was thinking of trying to modify this to work on more shells by 
moving the single quotes around the entire arguments, as they are 
parsed by the env command anyways. So it'd look like "exec env 
'TERM=%s'..." instead.

Is that reasonable? Would this break something I don't understand?

For context, here is where tramp-open-shell is located:
http://git.savannah.gnu.org/cgit/tramp.git/tree/lisp/tramp-sh.el#n4018

Thanks!

 //  codemac