[Bug-AUCTeX] AUC TeX patch (user was sometimes not queried regarding master file)

[Michael Ernst]

Suppose TeX-master-file is nil when visiting a file that contains no local
variables section that overrides TeX-master-file.  The user should be
queried for the name of the master file, and a local variables block should
be added to the end of the current buffer.  However,
VirTeX-common-initialization includes:

  (add-hook 'find-file-hooks
            (lambda ()
              ;; Check if we are looking at a new or shared file.
              (when (or (not (file-exists-p (buffer-file-name)))
                        (eq TeX-master 'shared))
                (TeX-master-file nil nil t))
              (TeX-update-style t)) nil t))

If TeX-master-file is nil, the hook calls TeX-update-style.
TeX-update-style itself calls TeX-master-file with the ask argument set
to nil.  That call to TeX-master-file sets TeX-master to the current file
name, and the user is never queried.

Here is a solution that seems to work for me:

--- /usr/share/emacs/site-lisp/auctex/tex.el    2007-10-05 19:08:09.000000000 
+0200
+++ -   2008-02-08 02:47:48.697672357 +0100
@@ -2402,7 +2402,8 @@
            (lambda ()
              ;; Check if we are looking at a new or shared file.
              (when (or (not (file-exists-p (buffer-file-name)))
-                       (eq TeX-master 'shared))
+                       (eq TeX-master 'shared)
+                       (eq TeX-master nil))
                (TeX-master-file nil nil t))
              (TeX-update-style t)) nil t))