Faces: Force initialization of the tags-faces-regexp.

When `org-tag-faces' is set too late, the regexp
is not initialized properly.  This patch makes sure it is
initializes anyway.

lisp/ChangeLog

@@ -3,6 +3,7 @@
 	* org.el (org-scan-tags): Rescan for tags, to get the correct
 	upcase/downcase stuff.  This slows things down for now, but it
 	works.
+	(org-mode): Make sure the tag-faces regexp is initialized.
 
 	* org-export-latex.el (org-export-latex-links): Fix bug with
 	undefined label.

lisp/org.el

@@ -3421,6 +3421,9 @@ The following commands are available:
 	       (if (stringp org-ellipsis) org-ellipsis "..."))))
     (setq buffer-display-table org-display-table))
   (org-set-regexps-and-options)
+  (when (and org-tag-faces (not org-tags-special-faces-re))
+    ;; tag faces set outside customize.... force initialization.
+    (org-set-tag-faces 'org-tag-faces org-tag-faces))
   ;; Calc embedded
   (org-set-local 'calc-embedded-open-mode "# ")
   (modify-syntax-entry ?# "<")