Merge branch 'fix_common_serialization' into 'master'

Fix object existence check in common serialiser

See merge request !326

beat/web/common/serializers.py

@@ -351,7 +351,7 @@ class ContributionCreationSerializer(serializers.ModelSerializer):
             )
 
         if self.Meta.model.objects.filter(
-            author__username__iexact=user, name=name, version=version
+            author=user, name=name, version=version
         ).exists():
             raise serializers.ValidationError(
                 "{} {} version {} already exists on this account".format(