[PATCH] fix first `save-buffer' with `break-hardlink-on-save' set

[Nix]

Currently, on bzr head, if `break-hardlink-on-save' is set, you can only
overwrite existing files: you cannot write new ones: attempts to write
new ones throws a Lisp error. This is because `basic-save-2' calls
`file-nlinks' without consideration of whether the file exists already,
and (> nil 1) is an error.

Fix below. (I'm not sure if, in the Bazaar world, you prefer to have
ChangeLogs incorporated in the diff itself. I'm sticking to pre-Bazaar
conventions for now.)

2011-05-15  Nix  <address@hidden>

        * files.el (basic-save-buffer-2): Only check `file-nlinks' and
        directory writability if the file already exists.

Index: emacs/lisp/files.el
===================================================================
--- emacs.orig/lisp/files.el    2011-05-15 16:36:56.187046000 +0100
+++ emacs/lisp/files.el 2011-05-15 16:41:26.832058984 +0100
@@ -4516,12 +4516,13 @@
     (let* ((dir (file-name-directory buffer-file-name))
            (dir-writable (file-writable-p dir)))
       (if (or (and file-precious-flag dir-writable)
-              (and break-hardlink-on-save
-                   (> (file-nlinks buffer-file-name) 1)
-                   (or dir-writable
-                       (error (concat (format
-                                       "Directory %s write-protected; " dir)
-                                      "cannot break hardlink when saving")))))
+             (and break-hardlink-on-save
+                  (file-exists-p buffer-file-name)
+                  (> (file-nlinks buffer-file-name) 1)
+                  (or dir-writable
+                      (error (concat (format
+                                      "Directory %s write-protected; " dir)
+                                     "cannot break hardlink when saving")))))
          ;; Write temp name, then rename it.
          ;; This requires write access to the containing dir,
          ;; which is why we don't try it if we don't have that access.