sanity-check build target before running a chain-build

cli/koji

@@ -643,6 +643,14 @@ def handle_chain_build(options, session, args):
     if dest_tag['locked']:
         parser.error(_("Destination tag %s is locked" % dest_tag['name']))
 
+    # check that the destination tag is in the inheritance tree of the build tag
+    # otherwise there is no way that a chain-build can work
+    ancestors = session.getFullInheritance(build_target['build_tag'])
+    if dest_tag['id'] not in [ancestor['parent_id'] for ancestor in ancestors]:
+        print _("Packages in destination tag %(dest_tag_name)s are not inherited by build tag %(build_tag_name)s" % build_target)
+        print _("Target %s is not usable for a chain-build" % build_target['name'])
+        return 1
+
     sources = args[1:]
     
     srpms = {}