If you un-install libvirt and re-install it, you get a warning

from the post-install script:

  Installing     : libvirt
  ln: creating symbolic link `/etc/libvirt/qemu/networks/autostart/default.xml': File exists

See https://bugzilla.redhat.com/462011

ChangeLog

+Wed Jan 21 10:48:12 IST 2009 Mark McLoughlin <markmc@redhat.com>
+
+	If you un-install libvirt and re-install it, you get a warning
+	from the post-install script:
+
+	  Installing     : libvirt
+	  ln: creating symbolic link `/etc/libvirt/qemu/networks/autostart/default.xml': File exists
+
+	See https://bugzilla.redhat.com/462011
+
+	* libvirt.spec.in: don't create networks/default.xml if it
+	already exists.
+
 Tue Jan 20 22:39:53 GMT 2009 Daniel P. Berrange <berrange@redhat.com>
 
 	Properly handle daemon restarts with storage driver

libvirt.spec.in

@@ -294,7 +294,7 @@ rm -fr %{buildroot}
 # or on the first upgrade from a non-network aware libvirt only.
 # We check this by looking to see if the daemon is already installed
 /sbin/chkconfig --list libvirtd 1>/dev/null 2>&1
-if [ $? != 0 ]
+if [ $? != 0 -a ! -f %{_sysconfdir}/libvirt/qemu/networks/default.xml ]
 then
     UUID=`/usr/bin/uuidgen`
     sed -e "s,</name>,</name>\n  <uuid>$UUID</uuid>," \