Use generic `display-buffer-alist' instead of mode-specific customizations.

* lisp/shell.el (shell-display-buffer-actions): Remove,
use `display-buffer-alist' instead.

etc/NEWS

@@ -193,9 +193,10 @@ Unicode standards.
 
 When you invoke `shell' interactively, the *shell* buffer will now
 display in a new window.  However, you can customize this behavior via
-the new `shell-display-buffer-actions' variable.  For example, to get
+the `display-buffer-alist' variable.  For example, to get
 the old behavior -- *shell* buffer displays in current window -- use
-(setq shell-display-buffer-actions '(display-buffer-same-window)).
+(add-to-list 'display-buffer-alist
+     '("^\\*shell\\*$" . (display-buffer-same-window))).
 
 ** ido
 *** New command `ido-bury-buffer-at-head' bound to C-S-b

lisp/ChangeLog

+2015-01-06  Sam Steingold  <sds@gnu.org>
+
+	* shell.el (shell-display-buffer-actions): Remove,
+	use `display-buffer-alist' instead.
+
 2015-01-05  Dmitry Gutov  <dgutov@yandex.ru>
 	* progmodes/xref.el (xref--insert-xrefs): Add `help-echo' property

lisp/shell.el

@@ -309,13 +309,6 @@ for Shell mode only."
 		 (const :tag "on" t))
   :group 'shell)
 
-(defcustom shell-display-buffer-actions display-buffer-base-action
-  "The `display-buffer' actions for the `*shell*' buffer."
-  :type display-buffer--action-custom-type
-  :risky t
-  :version "25.1"
-  :group 'shell)
-
 (defvar shell-dirstack nil
   "List of directories saved by pushd in this buffer's shell.
 Thus, this does not include the shell's current directory.")
@@ -726,7 +719,7 @@ Otherwise, one argument `-i' is passed to the shell.
 
   ;; The buffer's window must be correctly set when we call comint (so
   ;; that comint sets the COLUMNS env var properly).
-  (pop-to-buffer buffer shell-display-buffer-actions)
+  (pop-to-buffer buffer)
   (unless (comint-check-proc buffer)
     (let* ((prog (or explicit-shell-file-name
 		     (getenv "ESHELL") shell-file-name))