cli: check # of args in handle_set_build_volume()

cli/koji

@@ -2290,6 +2290,8 @@ def handle_set_build_volume(options, session, args):
     parser = OptionParser(usage=usage)
     parser.add_option("-v", "--verbose", action="store_true", help=_("Be verbose"))
     (options, args) = parser.parse_args(args)
+    if len(args) < 2:
+        parser.error("You must provide a volume and at least one build")
     volinfo = session.getVolume(args[0])
     if not volinfo:
         print("No such volume: %s" % args[0])