Backport commit 8832cc5f9 from Emacs

* lisp/ob-abc.el (org-babel-expand-body:abc, org-babel-execute:abc):
* lisp/ob-forth.el (org-babel-forth-session-execute):
Add backslash in regexp for correctness.
* lisp/org-list.el (org-plain-list-ordered-item-terminator):
Add backslash in doc comment so that it appears as intended.

Fix some ineffective backslashes in string literals
8832cc5f91a420db6bea65f381a3fb3597eb7523
Mattias Engdegård
Sat Mar 16 11:38:58 2019 -0700

lisp/ob-abc.el

@@ -47,7 +47,7 @@
 	     (value (cdr pair)))
 	 (setq body
 	       (replace-regexp-in-string
-		(concat "\$" (regexp-quote name))
+		(concat "\\$" (regexp-quote name))
 		(if (stringp value) value (format "%S" value))
 		body))))
      vars)
@@ -59,7 +59,7 @@
   (message "executing Abc source code block")
   (let* ((cmdline (cdr (assq :cmdline params)))
 	 (out-file (let ((file (cdr (assq :file params))))
-		     (if file (replace-regexp-in-string "\.pdf$" ".ps" file)
+		     (if file (replace-regexp-in-string "\\.pdf$" ".ps" file)
 		       (error "abc code block requires :file header argument"))))
 	 (in-file (org-babel-temp-file "abc-"))
 	 (render (concat "abcm2ps" " " cmdline

lisp/ob-forth.el

@@ -53,7 +53,7 @@ This function is called by `org-babel-execute-src-block'"
 (defun org-babel-forth-session-execute (body params)
   (require 'forth-mode)
   (let ((proc (forth-proc))
-	(rx " \\(\n:\\|compiled\n\\\|ok\n\\)")
+	(rx " \\(\n:\\|compiled\n\\|ok\n\\)")
 	(result-start))
     (with-current-buffer (process-buffer (forth-proc))
       (mapcar (lambda (line)

lisp/org-list.el

@@ -221,7 +221,7 @@ into
 
 (defcustom org-plain-list-ordered-item-terminator t
   "The character that makes a line with leading number an ordered list item.
-Valid values are ?. and ?\).  To get both terminators, use t.
+Valid values are ?. and ?\\).  To get both terminators, use t.
 
 This variable needs to be set before org.el is loaded.  If you
 need to make a change while Emacs is running, use the customize