fix nested runner configuration

Author: scriptonist

lib/runner/nested-request.js

@@ -129,7 +129,8 @@ function runNestedRequest ({ executionId, isExecutionSkipped, vaultSecrets, item
                         // Reuse current run's sandbox host across nested executions
                         external: true,
                         instance: self.host
-                    }
+                    },
+                    customParallelIterations: false
                 },
                 function (err, run) {
                     let exceptionForThisRequest = null,