Do not retry processing when there is no picture

pictures/tasks.py

@@ -33,11 +33,15 @@ def _process_picture(
     old = old or []
     storage = utils.reconstruct(*storage)
     if new:
-        with storage.open(file_name) as fs:
-            with Image.open(fs) as img:
-                for picture in new:
-                    picture = utils.reconstruct(*picture)
-                    picture.save(img)
+        try:
+            with storage.open(file_name) as fs:
+                with Image.open(fs) as img:
+                    for picture in new:
+                        picture = utils.reconstruct(*picture)
+                        picture.save(img)
+        except FileNotFoundError:
+            # The file no longer exists (for example, because it was deleted or replaced).
+            return
 
     for picture in old:
         picture = utils.reconstruct(*picture)

tests/test_tasks.py

@@ -22,5 +22,20 @@ def test_process_picture__file_cannot_be_reopened(image_upload_file):
     )
 
 
+@pytest.mark.django_db
+def test_process_picture__file_missing(image_upload_file):
+    obj = SimpleModel.objects.create(picture=image_upload_file)
+    setattr(
+        obj.picture.file,
+        "open",
+        Mock(side_effect=FileNotFoundError("The file does not exist anymore.")),
+    )
+    tasks._process_picture(
+        obj.picture.storage.deconstruct(),
+        obj.picture.name,
+        new=[i.deconstruct() for i in obj.picture.get_picture_files_list()],
+    )
+
+
 def test_noop():
     tasks.noop()  # does nothing