ob-ruby: Work around long line input

* lisp/ob-ruby.el (org-babel-ruby-var-to-ruby): Some comint buffers
are not able to process more than 4096 characters in one line - the
rest of the line can be silently ignored.  Work around this by
splitting list vars to multiple lines.

Link: https://orgmode.org/list/87pm3ut3zi.fsf@localhost

lisp/ob-ruby.el

@@ -140,7 +140,7 @@ This function is called by `org-babel-execute-src-block'."
 Convert an elisp value into a string of ruby source code
 specifying a variable of the same value."
   (if (listp var)
-      (concat "[" (mapconcat #'org-babel-ruby-var-to-ruby var ", ") "]")
+      (concat "[" (mapconcat #'org-babel-ruby-var-to-ruby var ", \n") "]")
     (if (eq var 'hline)
 	org-babel-ruby-hline-to
       (format "%S" var))))