Backport commit 4acdd7fe5 from Emacs

* lisp/ob-core.el (org-babel-remove-temporary-directory):
Use (rx (or (not ".") "...")), translated into "[^.]\\|\\.\\.\\.", to
match anything but "." and "..".

Fix edge case errors in filename-matching regexps
4acdd7fe58ae9f94102afeca67b0383141d597da
Mattias Engdegård
Tue Apr 14 12:25:16 2020 +0200

Note(km): Replaced bare "." with (any ".") for Emacs < 27
compatibility.  4acdd7fe5 was on the emacs-27 branch, but a commit on
their master (d5a7df8c0) will supersede this.

lisp/ob-core.el

@@ -3059,7 +3059,9 @@ of `org-babel-temporary-directory'."
 		    (delete-file file)))
 		;; We do not want to delete "." and "..".
 		(directory-files org-babel-temporary-directory 'full
-				 "^\\([^.]\\|\\.\\([^.]\\|\\..\\)\\).*"))
+				 ;; Note: Use `any' for compatibility
+				 ;; with Emacs < 27.
+				 (rx (or (not (any ".")) "..."))))
 	  (delete-directory org-babel-temporary-directory))
       (error
        (message "Failed to remove temporary Org-babel directory %s"