fix pascal_voc import bug (#4647)

* fix  pascal_voc import bug

* Add tests

* Fix black

* Small fixes

* Fix test

* Fix black

* Update Changelog

* Fix Changelog

* Fixes

* Remove unnecessary changes

* Remove unnecessary changes

* Join tests

* Small fix

* Fixes

* Fix pylint

* Remove unused import

* Small fix
Co-authored-by: Nyasakova-anastasia <yasakova_anastasiya@mail.ru>

CHANGELOG.md

@@ -64,6 +64,7 @@ non-ascii paths while adding files from "Connected file share" (issue #4428)
 - Extra rerenders of different pages with each click (<https://github.com/opencv/cvat/pull/5178>)
 - Skeleton points exported out of order in the COCO Keypoints format
   (<https://github.com/opencv/cvat/issues/5048>)
+- PASCAL VOC 1.1 can't import dataset (<https://github.com/opencv/cvat/pull/4647>)
 - Changing an object causes current z layer to be set to the maximum (<https://github.com/opencv/cvat/pull/5145>)
 - Job assignee can not resolve an issue (<https://github.com/opencv/cvat/pull/5167>)
 - Create manifest with cvat/server docker container command (<https://github.com/opencv/cvat/pull/5172>)

cvat/apps/dataset_manager/bindings.py

@@ -1895,6 +1895,9 @@ def load_dataset_data(project_annotation, dataset: dm.Dataset, project_data):
     else:
         for label in dataset.categories()[dm.AnnotationType.label].items:
             if not project_annotation.db_project.label_set.filter(name=label.name).exists():
+                if label.name == "background":
+                    dataset.transform("remap_labels", mapping={"background": ""}, default="keep")
+                    continue
                 raise CvatImportError(f'Target project does not have label with name "{label.name}"')
     for subset_id, subset in enumerate(dataset.subsets().values()):
         job = rq.get_current_job()

tests/python/rest_api/test_projects.py

@@ -458,10 +458,11 @@ class TestImportExportDatasetProject:
             )
             assert response.status == HTTPStatus.ACCEPTED
 
-    @pytest.mark.parametrize("format_name", ("ImageNet 1.0", "Datumaro 1.0"))
+    @pytest.mark.parametrize("format_name", ("Datumaro 1.0", "ImageNet 1.0", "PASCAL VOC 1.1"))
     def test_can_import_export_dataset_with_some_format(self, format_name):
         # https://github.com/opencv/cvat/issues/4410
         # https://github.com/opencv/cvat/issues/4850
+        # https://github.com/opencv/cvat/issues/4621
         username = "admin1"
         project_id = 4