Backport commit 67a8bdb90 from Emacs

* lisp/ob-picolisp.el (org-babel-execute:picolisp):
* lisp/ob-screen.el (org-babel-default-header-args:screen): Use
null-device.  (Bug#3736)

Use null-device where appropriate
67a8bdb90c9b5865b7f17290c7135b1a5458c36d
Michael Albinus
Wed Nov 25 22:13:33 2020 +0100

[km] Resolved conflict in ob-screen.  "/dev/null" was relocated to
     org-babel-default-header-args in 0ab117bc5 (ob-screen: Accept
     :screenrc header argument, 2020-07-14).

lisp/ob-picolisp.el

@@ -111,11 +111,11 @@ This function is called by `org-babel-execute-src-block'."
           (cond
            ((or (member "code" result-params)
                 (member "pp" result-params))
-            (format "(pretty (out \"/dev/null\" %s))" full-body))
+            (format "(pretty (out \"%s\" %s))" null-device full-body))
            ((and (member "value" result-params) (not session))
-            (format "(print (out \"/dev/null\" %s))" full-body))
+            (format "(print (out \"%s\" %s))" null-device full-body))
            ((member "value" result-params)
-            (format "(out \"/dev/null\" %s)" full-body))
+            (format "(out \"%s\" %s)" null-device full-body))
            (t full-body)))
          (result
           (if (not (string= session-name "none"))

lisp/ob-screen.el

@@ -40,8 +40,8 @@
 In case you want to use a different screen than one selected by your $PATH")
 
 (defvar org-babel-default-header-args:screen
-  '((:results . "silent") (:session . "default") (:cmd . "sh")
-    (:terminal . "xterm") (:screenrc . "/dev/null"))
+  `((:results . "silent") (:session . "default") (:cmd . "sh")
+    (:terminal . "xterm") (:screenrc . ,null-device))
   "Default arguments to use when running screen source blocks.")
 
 (defun org-babel-execute:screen (body params)