TF test_grad_summaries small fix

Needed now because LR meta info reads LR

tests/test_TFEngine.py

@@ -5050,6 +5050,7 @@ def test_grad_summaries():
     print("extern data:", engine.config.typed_value("extern_data"))
 
     engine.init_train_from_config()
+    engine.init_train_epoch()
 
     def extra_fetches_cb(summary_proto):
         """
@@ -5071,7 +5072,9 @@ def extra_fetches_cb(summary_proto):
         max_seqs=100,
         used_data_keys=engine.network.used_data_keys,
     )
-    forwarder = Runner(
+
+    engine.updater.set_learning_rate(engine.learning_rate, session=engine.tf_session)
+    trainer = Runner(
         engine=engine,
         dataset=train_data,
         batches=batches,
@@ -5082,8 +5085,8 @@ def extra_fetches_cb(summary_proto):
         },
         extra_fetches_callback=extra_fetches_cb,
     )
-    forwarder.run(report_prefix="test_grad_summaries")
-    if not forwarder.finalized:
+    trainer.run(report_prefix="test_grad_summaries")
+    if not trainer.finalized:
         raise Exception("Error happened. Exit now.")