W&B mosaic log bug fix (#1949)

train.py

@@ -318,7 +318,7 @@ def train(hyp, opt, device, tb_writer=None, wandb=None):
                     # if tb_writer:
                     #     tb_writer.add_image(f, result, dataformats='HWC', global_step=epoch)
                     #     tb_writer.add_graph(model, imgs)  # add model to tensorboard
-                elif plots and ni > 3 and wandb:
+                elif plots and ni == 10 and wandb:
                     wandb.log({"Mosaics": [wandb.Image(str(x), caption=x.name) for x in save_dir.glob('train*.jpg')
                                            if x.exists()]})