Fix bug with resume (#8912)

train.py

@@ -167,6 +167,7 @@ def train(hyp, opt, device, callbacks):  # hyp is path/to/hyp.yaml or hyp dictio
     # Resume
     best_fitness, start_epoch = 0.0, 0
     if pretrained:
+        if resume:
             best_fitness, start_epoch, epochs = smart_resume(ckpt, optimizer, ema, weights, epochs, resume)
         del ckpt, csd