Remove strict_optional=False for models/target_python.py.

setup.cfg

@@ -59,9 +59,6 @@ strict_optional = False
 [mypy-pip/_internal/models/link]
 strict_optional = False
 
-[mypy-pip/_internal/models/target_python]
-strict_optional = False
-
 [mypy-pip/_internal/operations/check]
 strict_optional = False
 

src/pip/_internal/utils/misc.py

@@ -118,7 +118,7 @@ def get_pip_version():
 
 
 def normalize_version_info(py_version_info):
-    # type: (Optional[Tuple[int, ...]]) -> Optional[Tuple[int, int, int]]
+    # type: (Tuple[int, ...]) -> Tuple[int, int, int]
     """
     Convert a tuple of ints representing a Python version to one of length
     three.
@@ -129,9 +129,6 @@ def normalize_version_info(py_version_info):
     :return: a tuple of length three if `py_version_info` is non-None.
         Otherwise, return `py_version_info` unchanged (i.e. None).
     """
-    if py_version_info is None:
-        return None
-
     if len(py_version_info) < 3:
         py_version_info += (3 - len(py_version_info)) * (0,)
     elif len(py_version_info) > 3:

tests/unit/test_utils.py

@@ -739,7 +739,6 @@ class TestGlibc(object):
 
 
 @pytest.mark.parametrize('version_info, expected', [
-    (None, None),
     ((), (0, 0, 0)),
     ((3, ), (3, 0, 0)),
     ((3, 6), (3, 6, 0)),