Etags completion problem for local tags table

[Radey Shouman <shouman@comcast.net>]

In (at least) emacs 22.1, completing reads for find-tag and list-tags
will use the global tags table list even if a local tags file has
been specified using a prefix argument for visit-tags-table.

To reproduce, visit two files, in the first buffer visit a tags file
globally, in the second a different tags file locally.  From the
second buffer, try M.[TAB] .  The tag list displayed will correspond
to the first, globally visited, tags file.

A patch that works for me is appended.

*** etags.el.dist	2007-01-21 03:20:46.000000000 -0500
--- etags.el	2008-02-19 17:46:44.592353300 -0500
***************
*** 257,262 ****
--- 257,264 ----
    "Function to do the work of `tags-included-tables' (which see).")
  (defvar verify-tags-table-function nil
    "Function to return t iff current buffer contains valid tags file.")
+ (defvar etags-calling-buffer nil
+   "Buffer from which a completing read was made, so we can determine the appropriate tags file to visit.")
  \f
  ;; Initialize the tags table in the current buffer.
  ;; Returns non-nil iff it is a valid tags table.  On
***************
*** 315,321 ****
        (setq file tags-file-name)))
    (if local
        ;; Set the local value of tags-file-name.
!       (set (make-local-variable 'tags-file-name) file)
      ;; Set the global value of tags-file-name.
      (setq-default tags-file-name file)))
  
--- 317,325 ----
        (setq file tags-file-name)))
    (if local
        ;; Set the local value of tags-file-name.
!       (progn
!         (set (make-local-variable 'tags-file-name) file)
!         (set (make-local-variable 'tags-table-list) nil))
      ;; Set the global value of tags-file-name.
      (setq-default tags-file-name file)))
  
***************
*** 751,756 ****
--- 755,762 ----
  	  (let (current-table combined-table)
  	    (message "Making tags completion table for %s..." buffer-file-name)
  	    (save-excursion
+               (if etags-calling-buffer
+                   (set-buffer etags-calling-buffer))
  	      ;; Iterate over the current list of tags tables.
  	      (while (visit-tags-table-buffer (and combined-table t))
  		;; Find possible completions in this table.
***************
*** 772,777 ****
--- 778,785 ----
  ;; but builds tags-completion-table on demand.
  (defun tags-complete-tag (string predicate what)
    (save-excursion
+     (if etags-calling-buffer
+         (set-buffer etags-calling-buffer))
      ;; If we need to ask for the tag table, allow that.
      (let ((enable-recursive-minibuffers t))
        (visit-tags-table-buffer))
***************
*** 781,787 ****
  \f
  ;; Read a tag name from the minibuffer with defaulting and completion.
  (defun find-tag-tag (string)
!   (let* ((completion-ignore-case (if (memq tags-case-fold-search '(t nil))
  				     tags-case-fold-search
  				   case-fold-search))
  	 (default (funcall (or find-tag-default-function
--- 789,796 ----
  \f
  ;; Read a tag name from the minibuffer with defaulting and completion.
  (defun find-tag-tag (string)
!   (let* ((etags-calling-buffer (current-buffer))
!          (completion-ignore-case (if (memq tags-case-fold-search '(t nil))
  				     tags-case-fold-search
  				   case-fold-search))
  	 (default (funcall (or find-tag-default-function
***************
*** 1834,1839 ****
--- 1843,1850 ----
  \f
  (defun tags-complete-tags-table-file (string predicate what)
    (save-excursion
+     (if etags-calling-buffer
+         (set-buffer etags-calling-buffer))
      ;; If we need to ask for the tag table, allow that.
      (let ((enable-recursive-minibuffers t))
        (visit-tags-table-buffer))