livemedia-creator: Check kickstart for shutdown (#1207959)

When using virt with livemedia-creator the kickstart needs to include
shutdown to make sure it doesn't hang at the end of the installation.

src/sbin/livemedia-creator

@@ -38,6 +38,7 @@ from math import ceil
 # Use pykickstart to calculate disk image size
 from pykickstart.parser import KickstartParser
 from pykickstart.version import makeVersion
+from pykickstart.constants import KS_SHUTDOWN
 
 # Use Mako templates for appliance builder descriptions
 from mako.template import Template
@@ -1338,6 +1339,9 @@ def main():
                 errors.append("Filesystem images must use a single / part, not autopart or "
                               "multiple partitions. swap is allowed but not used.")
 
+        if not opts.no_virt and ks.handler.reboot.action != KS_SHUTDOWN:
+            errors.append("The kickstart must include shutdown when using virt installation.")
+
         if errors:
             list(log.error(e) for e in errors)
             sys.exit(1)