fix typecheck script

Author: mkurnikov

scripts/typecheck_tests.py

@@ -26,7 +26,6 @@
 ]
 TESTS_DIRS = [
     'absolute_url_overrides',
-    # 'admin_*'
 ]
 
 
@@ -76,13 +75,9 @@ def check_with_mypy(abs_path: Path, config_file_path: Path) -> int:
         repo = Repo.clone_from('https://github.com/django/django.git', repo_directory)
     else:
         repo = Repo(repo_directory)
-        repo.remote().pull(DJANGO_COMMIT_SHA)
-
-    branch = repo.heads[DJANGO_BRANCH]
-    branch.checkout()
-    assert repo.active_branch.name == DJANGO_BRANCH
-    assert repo.active_branch.commit.hexsha == DJANGO_COMMIT_SHA
+        repo.remotes['origin'].pull(DJANGO_BRANCH)
 
+    repo.git.checkout(DJANGO_COMMIT_SHA)
     for dirname in TESTS_DIRS:
         paths = glob.glob(str(tests_root / dirname))
         for path in paths: