blktap2: a little fix to xen-hotplug-cleanup

Signed-off-by: James (Song Wei) <jsong@novell.com>
xen-unstable changeset:   21129:bf74d9c31674
xen-unstable date:        Mon Apr 12 07:23:21 2010 +0100

tools/hotplug/Linux/xen-hotplug-cleanup

@@ -21,7 +21,7 @@ if [ "$vm" != "" ]; then
 
   # if the vm path does not exist and the device class is 'vbd' then we may have
   # a tap2 device
-  if [ $(xenstore-read "$vm_dev" 2>/dev/null) != "" ] \
+  if [ "$(xenstore-read "$vm_dev" 2>/dev/null)" != "" ] \
        && [ "${path_array[1]}" = "vbd" ]; then
     vm_dev="$vm/device/tap2/${path_array[3]}"
   fi