auto_augment: img_shape broken (open-mmlab#6259)

* check/correct img.shape

* check/correct img.shape

* simpler fix for img_shape

* failtest Shear, Translate

* fix also _shear_img, _translate_img

* flake8

mmdet/datasets/pipelines/auto_augment.py

@@ -200,6 +200,7 @@ def _shear_img(self,
                 border_value=self.img_fill_val,
                 interpolation=interpolation)
             results[key] = img_sheared.astype(img.dtype)
+            results['img_shape'] = results[key].shape
 
     def _shear_bboxes(self, results, magnitude):
         """Shear the bboxes."""
@@ -421,6 +422,7 @@ def _rotate_img(self, results, angle, center=None, scale=1.0):
             img_rotated = mmcv.imrotate(
                 img, angle, center, scale, border_value=self.img_fill_val)
             results[key] = img_rotated.astype(img.dtype)
+            results['img_shape'] = results[key].shape
 
     def _rotate_bboxes(self, results, rotate_matrix):
         """Rotate the bboxes."""
@@ -621,6 +623,7 @@ def _translate_img(self, results, offset, direction='horizontal'):
             img = results[key].copy()
             results[key] = mmcv.imtranslate(
                 img, offset, direction, self.img_fill_val).astype(img.dtype)
+            results['img_shape'] = results[key].shape
 
     def _translate_bboxes(self, results, offset):
         """Shift bboxes horizontally or vertically, according to offset."""