Fix "C-u M-!" when 'shell-command-dont-erase-buffer' is non-nil

* lisp/simple.el (shell-command-dont-erase-buffer): Clarify the
effect of the various values in the doc string.
(shell-command-save-pos-or-erase, shell-command): Don't move or
push point if the output will go to the current buffer.
(Bug#40690)
(shell-command): Mention 'shell-command-dont-erase-buffer' in the
doc string.

* test/lisp/simple-tests.el
(with-shell-command-dont-erase-buffer): Don't is shell quoting
'like this', as it doesn't work on MS-Windows; quote "like this"
instead.
(simple-tests-shell-command-dont-erase-buffer): Adapt the test to
the new modus operandi.

* doc/emacs/misc.texi (Single Shell): Document the effect of the
various values of 'shell-command-dont-erase-buffer'.

* etc/NEWS: Expand and reword the entry regarding changes in
'shell-command-dont-erase-buffer'.

1 files changed, 2 insertions, 2 deletions

diff --git a/test/lisp/simple-tests.el b/test/lisp/simple-tests.el
index 276df795fca..8c477165a4f 100644
--- a/test/lisp/simple-tests.el
+++ b/test/lisp/simple-tests.el
@@ -724,7 +724,7 @@ See Bug#21722."
             (,output-buf (if ,output-buffer-is-current ,caller-buf
                            (generate-new-buffer "output-buf")))
             (emacs (expand-file-name invocation-name invocation-directory))
-            (,command (format "%s -Q --batch --eval '(princ \"%s\")'"
+            (,command (format "%s -Q --batch --eval \"(princ \\\"%s\\\")\""
                               emacs ,str))
             (inhibit-message t))
        (unwind-protect
@@ -761,7 +761,7 @@ See Bug#21722."
          (expected-point `((beg-last-out . ,(1+ (length str)))
                            (end-last-out . ,(1+ (* 2 (length str))))
                            (save-point . 1))))
-    (dolist (output-buffer-is-current '(t ni))
+    (dolist (output-buffer-is-current '(nil))
       (with-shell-command-dont-erase-buffer str output-buffer-is-current
         (when (memq shell-command-dont-erase-buffer '(beg-last-out end-last-out save-point))
           (should (= (point) (alist-get shell-command-dont-erase-buffer expected-point))))))))