Fix imports.

dulwich/porcelain.py

@@ -136,11 +136,8 @@ from dulwich.protocol import (
     ZERO_SHA,
 )
 from dulwich.refs import (
-    ANNOTATED_TAG_SUFFIX,
     LOCAL_BRANCH_PREFIX,
     LOCAL_TAG_PREFIX,
-    strip_peeled_refs,
-    RefsContainer,
     _import_remote_refs,
 )
 from dulwich.repo import BaseRepo, Repo