Correction init docker_args

package

@@ -86,12 +86,14 @@ if __name__ == "__main__":
     kwargs = dict()
     kwargs['debug'] = args.debug
 
+    docker_args = []
+
     # Append custom arguments
     if len(args.override_run_flags) > 0:
         docker_args += args.override_run_flags
     else:
         # rkt run arguments
-        docker_args = [
+        docker_args += [
             "run",
             "--rm",
             "-v", "{:s}:/src:ro".format(project_dir),