fixups

Author: hauntsaninja

setup.cfg

@@ -40,6 +40,7 @@ ignore_missing_imports = True
 disallow_untyped_defs = True
 disallow_any_generics = True
 warn_unused_ignores = True
+no_implicit_optional = True
 
 [mypy-pip._vendor.*]
 ignore_errors = True

src/pip/_internal/utils/hashes.py

@@ -1,5 +1,5 @@
 import hashlib
-from typing import TYPE_CHECKING, BinaryIO, Dict, Iterable, List
+from typing import TYPE_CHECKING, BinaryIO, Dict, Iterable, List, Optional
 
 from pip._internal.exceptions import HashMismatch, HashMissing, InstallationError
 from pip._internal.utils.misc import read_chunks