File check_net_oldname.patch of Package virt-v2v

In some network configurations (e.g. macvtap), it is possible to see the
following error during the conversion:

 Use of uninitialized value $oldname in concatenation (.) or string at
 /usr/lib/perl5/vendor_perl/5.18.2/Sys/VirtConvert/Config.pm line 489.

Prevent the error by ensure $oldname and $oldtype are defined before
attempting to use them.

Index: virt-v2v-0.9.1/lib/Sys/VirtConvert/Config.pm
===================================================================
--- virt-v2v-0.9.1.orig/lib/Sys/VirtConvert/Config.pm
+++ virt-v2v-0.9.1/lib/Sys/VirtConvert/Config.pm
@@ -486,10 +486,12 @@ sub map_network
 
     my $mapping;
     foreach my $root (@search) {
-        ($mapping) = $root->findnodes
-            ("network[\@type='$oldtype' and \@name='$oldname']/network");
+        if (defined($oldtype) && defined($oldname)) {
+            ($mapping) = $root->findnodes
+                ("network[\@type='$oldtype' and \@name='$oldname']/network");
 
-        last if defined($mapping);
+            last if defined($mapping);
+        }
     }
 
     unless (defined($mapping)) {