Remove strict_optional=False for models/link.py.

Author: cjerdonek

setup.cfg

@@ -53,9 +53,6 @@ strict_optional = False
 [mypy-pip/_internal/models/format_control]
 strict_optional = False
 
-[mypy-pip/_internal/models/link]
-strict_optional = False
-
 [mypy-pip/_internal/operations/check]
 strict_optional = False
 

src/pip/_internal/models/link.py

@@ -206,5 +206,8 @@ def is_hash_allowed(self, hashes):
         """
         if not self.has_hash:
             return False
+        # Assert non-None so mypy knows self.hash_name and self.hash are str.
+        assert self.hash_name is not None
+        assert self.hash is not None
 
         return hashes.is_hash_allowed(self.hash_name, hex_digest=self.hash)