bug#71935: split-string-and-unquote mishandles dired-listing-switches with '

[Juri Linkov <juri@linkov.net>]

>>> 1. (setopt dired-listing-switches "-al --block-size='1")
>>> 2. C-x d /tmp/*
>
> If they are a single string, split it with split-string-and-unquote,
> then concatenate after running each one through shell-quote-argument.
> If they are a list of strings, quote each one before concatenating
> with mapconcat.

Ok, this seems to work:

diff --git a/lisp/files.el b/lisp/files.el
index 042b8e2d515..6ed07f02890 100644
--- a/lisp/files.el
+++ b/lisp/files.el
@@ -8195,9 +8193,11 @@ insert-directory
 				 "\\") ; Disregard Unix shell aliases!
 			       insert-directory-program
 			       " -d "
-			       (if (stringp switches)
-				   switches
-				 (mapconcat #'identity switches " "))
+			       (mapconcat #'shell-quote-argument
+                                          (if (stringp switches)
+				              (split-string-and-unquote switches)
+                                            switches)
+                                          " ")
 			       " -- "
 			       ;; Quote some characters that have
 			       ;; special meanings in shells; but