File hotplug-Linux-block-find-free-loop-fix.patch of Package xen.1589

--- xen-4.2.5-testing/tools/hotplug/Linux/block.orig	2015-02-18 14:59:01.000000000 -0700
+++ xen-4.2.5-testing/tools/hotplug/Linux/block	2015-02-18 15:00:07.000000000 -0700
@@ -21,7 +21,7 @@ find_free_loopback_helper() {
   local busy_devnum
   while read busy_devnum; do
     if [ "$next_devnum" != "$busy_devnum" ]; then
-      break
+      case "$busy_devnum" in *[0-9]*) break;; esac
     fi
     let next_devnum=$next_devnum+1
   done