Upgrade flake8 to 3.8.1

Co-Authored-By: Anthony Sottile <asottile@umich.edu>

.pre-commit-config.yaml

@@ -17,7 +17,7 @@ repos:
     exclude: .patch
 
 - repo: https://gitlab.com/pycqa/flake8
-  rev: 3.7.9
+  rev: 3.8.1
   hooks:
   - id: flake8
     exclude: tests/data

src/pip/_internal/commands/show.py

@@ -99,7 +99,7 @@ def search_packages_info(query):
             # RECORDs should be part of .dist-info metadatas
             if dist.has_metadata('RECORD'):
                 lines = dist.get_metadata_lines('RECORD')
-                paths = [l.split(',')[0] for l in lines]
+                paths = [line.split(',')[0] for line in lines]
                 paths = [os.path.join(dist.location, p) for p in paths]
                 file_list = [os.path.relpath(p, dist.location) for p in paths]
 

src/pip/_internal/operations/install/wheel.py

@@ -32,16 +32,21 @@ from pip._internal.models.direct_url import DIRECT_URL_METADATA_NAME, DirectUrl
 from pip._internal.utils.filesystem import adjacent_tmp_file, replace
 from pip._internal.utils.misc import captured_stdout, ensure_dir, hash_file
 from pip._internal.utils.temp_dir import TempDirectory
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING, cast
+from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 from pip._internal.utils.unpacking import current_umask, unpack_file
 from pip._internal.utils.wheel import parse_wheel
 
-if MYPY_CHECK_RUNNING:
+# Use the custom cast function at runtime to make cast work,
+# and import typing.cast when performing pre-commit and type
+# checks
+if not MYPY_CHECK_RUNNING:
+    from pip._internal.utils.typing import cast
+else:
     from email.message import Message
     import typing  # noqa F401
     from typing import (
         Dict, List, Optional, Sequence, Tuple, Any,
-        Iterable, Iterator, Callable, Set,
+        Iterable, Iterator, Callable, Set, IO, cast
     )
 
     from pip._internal.models.scheme import Scheme
@@ -607,7 +612,7 @@ def install_unpacked_wheel(
         # Python 2 (typing.BinaryIO), leading us to explicitly
         # cast to typing.IO[str] as a workaround
         # for bad Python 2 behaviour
-        record_file_obj = cast('typing.IO[str]', record_file)
+        record_file_obj = cast('IO[str]', record_file)
 
         writer = csv.writer(record_file_obj)
         writer.writerows(sorted_outrows(rows))  # sort to simplify testing

src/pip/_internal/utils/misc.py

@@ -541,7 +541,7 @@ class FakeFile(object):
     """Wrap a list of lines in an object with readline() to make
     ConfigParser happy."""
     def __init__(self, lines):
-        self._gen = (l for l in lines)
+        self._gen = iter(lines)
 
     def readline(self):
         try:

src/pip/_internal/wheel_builder.py

@@ -36,7 +36,8 @@ logger = logging.getLogger(__name__)
 
 
 def _contains_egg_info(
-        s, _egg_info_re=re.compile(r'([a-z0-9_.]+)-([a-z0-9_.!+-]+)', re.I)):
+        s, _egg_info_re=re.compile(r'([a-z0-9_.]+)-([a-z0-9_.!+-]+)',
+                                   re.IGNORECASE)):
     # type: (str, Pattern[str]) -> bool
     """Determine whether the string looks like an egg_info.
 

tests/functional/test_install_reqs.py

@@ -420,7 +420,7 @@ def test_install_with_extras_from_install(script, data):
     )
     result = script.pip_install_local(
         '-c', script.scratch_path / 'constraints.txt', 'LocalExtras[baz]')
-    assert script.site_packages / 'singlemodule.py'in result.files_created
+    assert script.site_packages / 'singlemodule.py' in result.files_created
 
 
 def test_install_with_extras_joined(script, data):
@@ -432,7 +432,7 @@ def test_install_with_extras_joined(script, data):
         '-c', script.scratch_path / 'constraints.txt', 'LocalExtras[baz]'
     )
     assert script.site_packages / 'simple' in result.files_created
-    assert script.site_packages / 'singlemodule.py'in result.files_created
+    assert script.site_packages / 'singlemodule.py' in result.files_created
 
 
 def test_install_with_extras_editable_joined(script, data):
@@ -443,7 +443,7 @@ def test_install_with_extras_editable_joined(script, data):
     result = script.pip_install_local(
         '-c', script.scratch_path / 'constraints.txt', 'LocalExtras[baz]')
     assert script.site_packages / 'simple' in result.files_created
-    assert script.site_packages / 'singlemodule.py'in result.files_created
+    assert script.site_packages / 'singlemodule.py' in result.files_created
 
 
 def test_install_distribution_full_union(script, data):