Index: openacs-4/packages/xowiki/tcl/xowiki-procs.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/xowiki/tcl/xowiki-procs.tcl,v
diff -u -N -r1.440 -r1.441
--- openacs-4/packages/xowiki/tcl/xowiki-procs.tcl	26 Aug 2011 15:53:40 -0000	1.440
+++ openacs-4/packages/xowiki/tcl/xowiki-procs.tcl	22 Oct 2011 09:16:27 -0000	1.441
@@ -821,9 +821,11 @@
         "delete from xowiki_tags where item_id = $item_id and user_id = $user_id"
 
     foreach tag [split $tags " ,;"] {
-      db_dml [my qn insert_tag] \
-          "insert into xowiki_tags (item_id,package_id, user_id, tag, time) \
-           values ($item_id, $package_id, $user_id, :tag, current_timestamp)"
+      if {$tag ne ""} {
+	db_dml [my qn insert_tag] \
+	    "insert into xowiki_tags (item_id,package_id, user_id, tag, time) \
+	      values ($item_id, $package_id, $user_id, :tag, current_timestamp)"
+      }
     }
     search::queue -object_id $revision_id -event UPDATE
   }