Do not blank a table cell after expanding a snippet

* lisp/org.el (org-self-insert-command): Do not blank a table cell if
  last command is `yas-expand'.

Thanks to Sébastien Vauban for reporting it.
<http://permalink.gmane.org/gmane.emacs.orgmode/92918>

lisp/org.el

@@ -19829,8 +19829,8 @@ overwritten, and the table is not marked as requiring realignment."
      (progn
        ;; check if we blank the field, and if that triggers align
        (and (featurep 'org-table) org-table-auto-blank-field
-	    (member last-command
-		    '(org-cycle org-return org-shifttab org-ctrl-c-ctrl-c yas-expand))
+	    (memq last-command
+		  '(org-cycle org-return org-shifttab org-ctrl-c-ctrl-c))
 	    (if (or (equal (char-after) ?\ ) (looking-at "[^|\n]*  |"))
 		;; got extra space, this field does not determine column width
 		(let (org-table-may-need-update) (org-table-blank-field))