save MODEL_VARIABLES in batchnorm freeze mode

tensorpack/models/batch_norm.py

@@ -45,9 +45,6 @@ def update_bn_ema(xn, batch_mean, batch_var, moving_mean, moving_var, decay):
     update_op2 = moving_averages.assign_moving_average(
         moving_var, batch_var, decay, zero_debias=False,
         name='var_ema_op')
-    # Only add to model var when we update them
-    add_model_variable(moving_mean)
-    add_model_variable(moving_var)
 
     # TODO add an option, and maybe enable it for replica mode?
     # with tf.control_dependencies([update_op1, update_op2]):
@@ -160,7 +157,10 @@ def BatchNorm(x, use_local_stat=None, decay=0.9, epsilon=1e-5,
 
     # maintain EMA only on one GPU is OK, even in replicated mode.
     # because training time doesn't use EMA
-    if ctx.is_main_training_tower and use_local_stat:
+    if ctx.is_main_training_tower:
+        add_model_variable(moving_mean)
+        add_model_variable(moving_var)
+        if use_local_stat:
             ret = update_bn_ema(xn, batch_mean, batch_var, moving_mean, moving_var, decay)
     else:
         ret = tf.identity(xn, name='output')