Index: openacs-4/packages/xowiki/tcl/xowiki-www-procs.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/xowiki/tcl/xowiki-www-procs.tcl,v
diff -u -r1.303 -r1.304
--- openacs-4/packages/xowiki/tcl/xowiki-www-procs.tcl	7 Mar 2012 08:11:32 -0000	1.303
+++ openacs-4/packages/xowiki/tcl/xowiki-www-procs.tcl	21 Mar 2012 12:01:18 -0000	1.304
@@ -1893,8 +1893,8 @@
       }
     }
     #my msg "validation returns $validation_errors errors"
-
-    if {$validation_errors == 0 && [::xo::cc form_parameter __current_revision_id ""] != [my revision_id]} {
+    set current_revision_id [::xo::cc form_parameter __current_revision_id ""]
+    if {$validation_errors == 0 && $current_revision_id ne "" && $current_revision_id != [my revision_id]} {
       set validation_errors [my mutual_overwrite_occurred]
     }