Why is 'activation=False' in upsample part?

[notabigfish]

Hi, I'm confused about the 209th line in model.py.
conv_decode4 = conv_layer_with_bn(upsample4, [7, 7, 64, 64], phase_train, False, name="conv_decode4")
Why is activation=False? According to the paper, ReLU is used in decoder, too.