Index: openacs-4/packages/xotcl-core/tcl/bgdelivery-procs.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/xotcl-core/tcl/bgdelivery-procs.tcl,v
diff -u -r1.17 -r1.18
--- openacs-4/packages/xotcl-core/tcl/bgdelivery-procs.tcl	4 Nov 2008 22:04:49 -0000	1.17
+++ openacs-4/packages/xotcl-core/tcl/bgdelivery-procs.tcl	26 Nov 2008 09:27:18 -0000	1.18
@@ -213,6 +213,14 @@
   #ns_log notice "expires-set $filename"
 
   if {[my write_headers $statuscode $mime_type $size]} {
+
+    if {$size == 0} {
+      # Tcl behaves differnt, when one tries to send 0 bytes via
+      # file_copy. So, we handle this special case here...
+      # There is actualy nothing to deliver....
+      return
+    }
+
     set errorMsg ""
     # Get the thread id and make sure the bgdelivery thread is already
     # running.