fix ema copy problem and correct config of ppyolo in static graph (#3370)

ppdet/engine/trainer.py

@@ -18,6 +18,7 @@ from __future__ import print_function
 
 import os
 import sys
+import copy
 import time
 import random
 import datetime
@@ -333,7 +334,7 @@ class Trainer(object):
 
             # apply ema weight on model
             if self.use_ema:
-                weight = self.model.state_dict()
+                weight = copy.deepcopy(self.model.state_dict())
                 self.model.set_dict(self.ema.apply())
 
             self._compose_callback.on_epoch_end(self.status)

static/configs/ppyolo/ppyolov2_reader.yml

@@ -17,7 +17,6 @@ TrainReader:
       beta: 1.5
     - !ColorDistort {}
     - !RandomExpand
-      ratio: 2.0
       fill_value: [123.675, 116.28, 103.53]
     - !RandomCrop {}
     - !RandomFlipImage