Description: skip ifindex check if interface setup script is given
 If an <interface ...> definition uses an external script, the interface
 possibly does not exist before qemu starts (set up by qemu or by the
 script). Skip the advance check for an ifindex.

--- libvirt-1.3.1.orig/src/qemu/qemu_command.c
+++ libvirt-1.3.1/src/qemu/qemu_command.c
@@ -8904,7 +8904,7 @@ qemuBuildInterfaceCommandLine(virCommand
          * macvtap device
          */
         if (virQEMUDriverIsPrivileged(driver) && nicindexes && nnicindexes &&
-            net->ifname) {
+            net->ifname && !net->script) {
             if (virNetDevGetIndex(net->ifname, &nicindex) < 0 ||
                 VIR_APPEND_ELEMENT(*nicindexes, *nnicindexes, nicindex) < 0)
                 goto cleanup;