Fix batch=-1 for exports (#3217)

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

ultralytics/yolo/engine/model.py

@@ -335,7 +335,7 @@ class YOLO:
         overrides['mode'] = 'export'
         if overrides.get('imgsz') is None:
             overrides['imgsz'] = self.model.args['imgsz']  # use trained imgsz unless custom value is passed
-        if overrides.get('batch') is None:
+        if 'batch' not in kwargs:
             overrides['batch'] = 1  # default to 1 if not modified
         args = get_cfg(cfg=DEFAULT_CFG, overrides=overrides)
         args.task = self.task

ultralytics/yolo/engine/trainer.py

@@ -229,7 +229,7 @@ class BaseTrainer:
         # Batch size
         if self.batch_size == -1:
             if RANK == -1:  # single-GPU only, estimate best batch size
-                self.batch_size = check_train_batch_size(self.model, self.args.imgsz, self.amp)
+                self.args.batch = self.batch_size = check_train_batch_size(self.model, self.args.imgsz, self.amp)
             else:
                 SyntaxError('batch=-1 to use AutoBatch is only available in Single-GPU training. '
                             'Please pass a valid batch size value for Multi-GPU DDP training, i.e. batch=16')