Make sure a URL is written to the output kickstart file.

pykickstart isn't setting ks.handler.url.seen when setting url.url, but
it does set seen when using the style in this patch.  Having seen set,
the URL line should be written to the kickstart file.

Patch written by Chris Lumens <clumens@redhat.com>

Signed-off-by: Dennis Gilmore <dennis@ausil.us>

builder/kojid

@@ -2880,7 +2880,7 @@ class OzImageTask(BaseTaskHandler):
             ks.handler.repo.repoList.append(repo_class(
                 baseurl=baseurl, name='koji-override-0'))
         # inject the URL of the install tree into the kickstart
-        ks.handler.url.url = install_tree
+        ks.handler.url(url=install_tree)
         return ks
 
     def writeKickstart(self, ksobj, ksname):