Fix that linter actually ignores deleted files and add a specific test for this

tests/fixtures.py

@@ -38,6 +38,8 @@ MULTI_COMMIT_PROJECT = os.path.join(
     _FIXTURES_FOLDER, 'test_project_multi_commit/')
 CORRECT_PROJECT = os.path.join(
     _FIXTURES_FOLDER, 'test_correct_project/')
+DELETED_MIGRATION_PROJECT = os.path.join(
+    _FIXTURES_FOLDER, 'test_deleted_migration_project/')
 
 NOT_DJANGO_GIT_PROJECT = os.path.join(
     _FIXTURES_FOLDER, 'test_git_project/')
@@ -46,7 +48,8 @@ NOT_GIT_DJANGO_PROJECT = os.path.join(
 
 ALL_GIT_PROJECTS = (
     NOT_DJANGO_GIT_PROJECT,
-    MULTI_COMMIT_PROJECT
+    MULTI_COMMIT_PROJECT,
+    DELETED_MIGRATION_PROJECT
 )