diff --git a/setup.cfg b/setup.cfg
index c0e5180a210095e4c4eaa879a09459e546bacf96..15bb672406a63afb14c18c144d2fcf2feef8d977 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -9,6 +9,7 @@ known_first_party =
     pip
     tests
 default_section = THIRDPARTY
+include_trailing_comma = true
 
 [flake8]
 # Ignoring unused imports since mypy would warn of that.
diff --git a/src/pip/_internal/basecommand.py b/src/pip/_internal/basecommand.py
index d7c643b70d363e152c939329b5b4e32ecbbf8176..c79a5f48607f72b14ff86c11f1aca6d80ef74a8b 100644
--- a/src/pip/_internal/basecommand.py
+++ b/src/pip/_internal/basecommand.py
@@ -10,13 +10,13 @@ import warnings
 
 from pip._internal import cmdoptions
 from pip._internal.baseparser import (
-    ConfigOptionParser, UpdatingDefaultsHelpFormatter
+    ConfigOptionParser, UpdatingDefaultsHelpFormatter,
 )
 from pip._internal.compat import WINDOWS
 from pip._internal.download import PipSession
 from pip._internal.exceptions import (
     BadCommand, CommandError, InstallationError, PreviousBuildDirError,
-    UninstallationError
+    UninstallationError,
 )
 from pip._internal.index import PackageFinder
 from pip._internal.locations import running_under_virtualenv
@@ -24,7 +24,7 @@ from pip._internal.req.req_file import parse_requirements
 from pip._internal.req.req_install import InstallRequirement
 from pip._internal.status_codes import (
     ERROR, PREVIOUS_BUILD_DIR_ERROR, SUCCESS, UNKNOWN_ERROR,
-    VIRTUALENV_NOT_FOUND
+    VIRTUALENV_NOT_FOUND,
 )
 from pip._internal.utils import deprecation
 from pip._internal.utils.logging import IndentingFormatter
diff --git a/src/pip/_internal/cmdoptions.py b/src/pip/_internal/cmdoptions.py
index cdba7acb1a6a378ff25bb7a981072ef08c363d34..eaabdbde6fcf9fdc17708c6f9d4544236b1a0d03 100644
--- a/src/pip/_internal/cmdoptions.py
+++ b/src/pip/_internal/cmdoptions.py
@@ -14,7 +14,7 @@ from functools import partial
 from optparse import SUPPRESS_HELP, Option, OptionGroup
 
 from pip._internal.index import (
-    FormatControl, fmt_ctl_handle_mutual_exclude, fmt_ctl_no_binary
+    FormatControl, fmt_ctl_handle_mutual_exclude, fmt_ctl_no_binary,
 )
 from pip._internal.locations import USER_CACHE_DIR, src_prefix
 from pip._internal.models import PyPI
diff --git a/src/pip/_internal/commands/install.py b/src/pip/_internal/commands/install.py
index 56f3fbb02ace6fe237b66ca73db643bfdefe76aa..cac15aac0e4538616a8763127de3d0ec92bfb7fb 100644
--- a/src/pip/_internal/commands/install.py
+++ b/src/pip/_internal/commands/install.py
@@ -10,7 +10,7 @@ from pip._internal import cmdoptions
 from pip._internal.basecommand import RequirementCommand
 from pip._internal.cache import WheelCache
 from pip._internal.exceptions import (
-    CommandError, InstallationError, PreviousBuildDirError
+    CommandError, InstallationError, PreviousBuildDirError,
 )
 from pip._internal.locations import distutils_scheme, virtualenv_no_global
 from pip._internal.operations.prepare import RequirementPreparer
diff --git a/src/pip/_internal/commands/list.py b/src/pip/_internal/commands/list.py
index 6593c407d7a5807098113dc5dcc64d1e8ff80c7d..905200282770f879a4d7b1541a0ae9c9fae32796 100644
--- a/src/pip/_internal/commands/list.py
+++ b/src/pip/_internal/commands/list.py
@@ -13,7 +13,7 @@ from pip._internal.exceptions import CommandError
 from pip._internal.index import PackageFinder
 from pip._internal.utils.deprecation import RemovedInPip11Warning
 from pip._internal.utils.misc import (
-    dist_is_editable, get_installed_distributions
+    dist_is_editable, get_installed_distributions,
 )
 from pip._internal.utils.packaging import get_installer
 
diff --git a/src/pip/_internal/configuration.py b/src/pip/_internal/configuration.py
index abdedb6967cb90dd8d38be94f382e9ea0f485286..6a05d624489e948c28cb96bfc5c82104bfb1c0c9 100644
--- a/src/pip/_internal/configuration.py
+++ b/src/pip/_internal/configuration.py
@@ -20,7 +20,7 @@ from pip._vendor.six.moves import configparser
 from pip._internal.exceptions import ConfigurationError
 from pip._internal.locations import (
     legacy_config_file, new_config_file, running_under_virtualenv,
-    site_config_files, venv_config_file
+    site_config_files, venv_config_file,
 )
 from pip._internal.utils.misc import ensure_dir, enum
 from pip._internal.utils.typing import MYPY_CHECK_RUNNING
diff --git a/src/pip/_internal/download.py b/src/pip/_internal/download.py
index 180ea77bfaf92e3676de31908e8c57b7f1d56e4b..d56a1bb3bb2493a1e06f51967ace54bc3582bb18 100644
--- a/src/pip/_internal/download.py
+++ b/src/pip/_internal/download.py
@@ -39,7 +39,7 @@ from pip._internal.utils.logging import indent_log
 from pip._internal.utils.misc import (
     ARCHIVE_EXTENSIONS, ask_path_exists, backup_dir, call_subprocess, consume,
     display_path, format_size, get_installed_version, rmtree, splitext,
-    unpack_file
+    unpack_file,
 )
 from pip._internal.utils.setuptools_build import SETUPTOOLS_SHIM
 from pip._internal.utils.temp_dir import TempDirectory
diff --git a/src/pip/_internal/index.py b/src/pip/_internal/index.py
index ee6651420f06149de1706a5bfdf4a534c5e49b6c..7c1c210b697a85f199e819826dd94ed5eab4da72 100644
--- a/src/pip/_internal/index.py
+++ b/src/pip/_internal/index.py
@@ -25,7 +25,7 @@ from pip._internal.compat import ipaddress
 from pip._internal.download import HAS_TLS, is_url, path_to_url, url_to_path
 from pip._internal.exceptions import (
     BestVersionAlreadyInstalled, DistributionNotFound, InvalidWheelFilename,
-    UnsupportedWheel
+    UnsupportedWheel,
 )
 from pip._internal.models import PyPI
 from pip._internal.pep425tags import get_supported
@@ -33,7 +33,7 @@ from pip._internal.utils.deprecation import RemovedInPip11Warning
 from pip._internal.utils.logging import indent_log
 from pip._internal.utils.misc import (
     ARCHIVE_EXTENSIONS, SUPPORTED_EXTENSIONS, cached_property, normalize_path,
-    splitext
+    splitext,
 )
 from pip._internal.utils.packaging import check_requires_python
 from pip._internal.wheel import Wheel, wheel_ext
diff --git a/src/pip/_internal/operations/freeze.py b/src/pip/_internal/operations/freeze.py
index adaa8d0936ae5af57ea251b6839a208e15fe8b36..4455f0c910c774b9a7e4dd235c11bcc85b72150d 100644
--- a/src/pip/_internal/operations/freeze.py
+++ b/src/pip/_internal/operations/freeze.py
@@ -15,7 +15,7 @@ from pip._internal.req import InstallRequirement
 from pip._internal.req.req_file import COMMENT_RE
 from pip._internal.utils.deprecation import RemovedInPip11Warning
 from pip._internal.utils.misc import (
-    dist_is_editable, get_installed_distributions
+    dist_is_editable, get_installed_distributions,
 )
 
 logger = logging.getLogger(__name__)
diff --git a/src/pip/_internal/operations/prepare.py b/src/pip/_internal/operations/prepare.py
index 0e2b7536abced7f4c965fb3ff418f9a9195db5bc..e1d8a2baa815a4a579d620431f9aa9aa9b423ed0 100644
--- a/src/pip/_internal/operations/prepare.py
+++ b/src/pip/_internal/operations/prepare.py
@@ -8,11 +8,11 @@ from pip._vendor import pkg_resources, requests
 
 from pip._internal.compat import expanduser
 from pip._internal.download import (
-    is_dir_url, is_file_url, is_vcs_url, unpack_url, url_to_path
+    is_dir_url, is_file_url, is_vcs_url, unpack_url, url_to_path,
 )
 from pip._internal.exceptions import (
     DirectoryUrlHashUnsupported, HashUnpinned, InstallationError,
-    PreviousBuildDirError, VcsHashUnsupported
+    PreviousBuildDirError, VcsHashUnsupported,
 )
 from pip._internal.utils.hashes import MissingHashes
 from pip._internal.utils.logging import indent_log
diff --git a/src/pip/_internal/req/req_install.py b/src/pip/_internal/req/req_install.py
index 43b85665bd6306473f18af83b1875dba7ee6129f..d3b9dd4280d3b94229c41f12eb63917290a5cae1 100644
--- a/src/pip/_internal/req/req_install.py
+++ b/src/pip/_internal/req/req_install.py
@@ -24,11 +24,11 @@ from pip._vendor.pkg_resources import RequirementParseError, parse_requirements
 from pip._internal import wheel
 from pip._internal.compat import native_str
 from pip._internal.download import (
-    is_archive_file, is_url, path_to_url, url_to_path
+    is_archive_file, is_url, path_to_url, url_to_path,
 )
 from pip._internal.exceptions import InstallationError, UninstallationError
 from pip._internal.locations import (
-    PIP_DELETE_MARKER_FILENAME, running_under_virtualenv
+    PIP_DELETE_MARKER_FILENAME, running_under_virtualenv,
 )
 from pip._internal.req.req_uninstall import UninstallPathSet
 from pip._internal.utils.deprecation import RemovedInPip11Warning
@@ -37,7 +37,7 @@ from pip._internal.utils.logging import indent_log
 from pip._internal.utils.misc import (
     _make_build_dir, ask_path_exists, backup_dir, call_subprocess,
     display_path, dist_in_site_packages, dist_in_usersite, ensure_dir,
-    get_installed_version, is_installable_dir, read_text_file, rmtree
+    get_installed_version, is_installable_dir, read_text_file, rmtree,
 )
 from pip._internal.utils.setuptools_build import SETUPTOOLS_SHIM
 from pip._internal.utils.temp_dir import TempDirectory
diff --git a/src/pip/_internal/req/req_uninstall.py b/src/pip/_internal/req/req_uninstall.py
index 31271a17c22705b7a46e7a091f963d2ab5de945f..a7c0870a7289fd0d04061e7b391af7e1623ee386 100644
--- a/src/pip/_internal/req/req_uninstall.py
+++ b/src/pip/_internal/req/req_uninstall.py
@@ -15,7 +15,7 @@ from pip._internal.locations import bin_py, bin_user
 from pip._internal.utils.logging import indent_log
 from pip._internal.utils.misc import (
     FakeFile, ask, dist_in_usersite, dist_is_local, egg_link_path, is_local,
-    normalize_path, renames
+    normalize_path, renames,
 )
 from pip._internal.utils.temp_dir import TempDirectory
 
diff --git a/src/pip/_internal/resolve.py b/src/pip/_internal/resolve.py
index 0c22ee9c92c13b4447c57875615e0687f54f9108..e84b6dc8511b3fc14801822d87154760e3495b4c 100644
--- a/src/pip/_internal/resolve.py
+++ b/src/pip/_internal/resolve.py
@@ -15,7 +15,7 @@ from itertools import chain
 
 from pip._internal.exceptions import (
     BestVersionAlreadyInstalled, DistributionNotFound, HashError, HashErrors,
-    UnsupportedPythonVersion
+    UnsupportedPythonVersion,
 )
 from pip._internal.req.req_install import InstallRequirement
 from pip._internal.utils.logging import indent_log
diff --git a/src/pip/_internal/utils/hashes.py b/src/pip/_internal/utils/hashes.py
index 3a4cd3e62c57cbc8d05403442661f40a5992ea10..8b909ba155c8c063ab52fc4a2fddbab3f4a78b94 100644
--- a/src/pip/_internal/utils/hashes.py
+++ b/src/pip/_internal/utils/hashes.py
@@ -5,7 +5,7 @@ import hashlib
 from pip._vendor.six import iteritems, iterkeys, itervalues
 
 from pip._internal.exceptions import (
-    HashMismatch, HashMissing, InstallationError
+    HashMismatch, HashMissing, InstallationError,
 )
 from pip._internal.utils.misc import read_chunks
 
diff --git a/src/pip/_internal/utils/misc.py b/src/pip/_internal/utils/misc.py
index d9ecbeb8302728d8286d14b12a3a4e7210004222..fa4c047277d827acc0bca84360890e6e7a15ceff 100644
--- a/src/pip/_internal/utils/misc.py
+++ b/src/pip/_internal/utils/misc.py
@@ -29,7 +29,7 @@ from pip._internal.compat import console_to_str, expanduser, stdlib_pkgs
 from pip._internal.exceptions import InstallationError
 from pip._internal.locations import (
     running_under_virtualenv, site_packages, user_site, virtualenv_no_global,
-    write_delete_marker_file
+    write_delete_marker_file,
 )
 
 if PY2:
diff --git a/src/pip/_internal/utils/ui.py b/src/pip/_internal/utils/ui.py
index 3e1f0e7a0d3cc87ab84b9b2f8b225c7bf94b98a7..8ade1e210a36d37c7af623f8b974838f84fc4bec 100644
--- a/src/pip/_internal/utils/ui.py
+++ b/src/pip/_internal/utils/ui.py
@@ -10,7 +10,7 @@ from signal import SIGINT, default_int_handler, signal
 from pip._vendor import six
 from pip._vendor.progress.bar import (
     Bar, ChargingBar, FillingCirclesBar, FillingSquaresBar, IncrementalBar,
-    ShadyBar
+    ShadyBar,
 )
 from pip._vendor.progress.helpers import HIDE_CURSOR, SHOW_CURSOR, WritelnMixin
 from pip._vendor.progress.spinner import Spinner
diff --git a/src/pip/_internal/wheel.py b/src/pip/_internal/wheel.py
index 31fc7b82670c7f64c59bc03b2d130a85e060c3f6..1df87db86d086dd58d97ce951472ab46ff280dc3 100644
--- a/src/pip/_internal/wheel.py
+++ b/src/pip/_internal/wheel.py
@@ -27,14 +27,14 @@ from pip._vendor.six import StringIO
 from pip._internal import pep425tags
 from pip._internal.download import path_to_url, unpack_url
 from pip._internal.exceptions import (
-    InstallationError, InvalidWheelFilename, UnsupportedWheel
+    InstallationError, InvalidWheelFilename, UnsupportedWheel,
 )
 from pip._internal.locations import (
-    PIP_DELETE_MARKER_FILENAME, distutils_scheme
+    PIP_DELETE_MARKER_FILENAME, distutils_scheme,
 )
 from pip._internal.utils.logging import indent_log
 from pip._internal.utils.misc import (
-    call_subprocess, captured_stdout, ensure_dir, read_chunks
+    call_subprocess, captured_stdout, ensure_dir, read_chunks,
 )
 from pip._internal.utils.setuptools_build import SETUPTOOLS_SHIM
 from pip._internal.utils.temp_dir import TempDirectory
diff --git a/tests/functional/test_freeze.py b/tests/functional/test_freeze.py
index 1846e729088bf5698f3197e2f96d9cab8557cd33..87c6038183cd0a79edfd7726bd6b2da277e1a353 100644
--- a/tests/functional/test_freeze.py
+++ b/tests/functional/test_freeze.py
@@ -8,7 +8,7 @@ import pytest
 
 from tests.lib import (
     _create_test_package, _create_test_package_with_srcdir, need_bzr,
-    need_mercurial
+    need_mercurial,
 )
 
 distribute_re = re.compile('^distribute==[0-9.]+\n', re.MULTILINE)
diff --git a/tests/functional/test_install.py b/tests/functional/test_install.py
index 9d137e8d1deef5d592ddd05359abfadb05f64380..62e51807b5436546f76ccb7734aa07a221d3b5e2 100644
--- a/tests/functional/test_install.py
+++ b/tests/functional/test_install.py
@@ -13,7 +13,7 @@ from pip._internal.utils.misc import rmtree
 from tests.lib import (
     _create_svn_repo, _create_test_package, create_test_package_with_setup,
     need_bzr, need_mercurial, path_to_url, pyversion, pyversion_tuple,
-    requirements_file
+    requirements_file,
 )
 from tests.lib.local_repos import local_checkout
 from tests.lib.path import Path
diff --git a/tests/functional/test_install_reqs.py b/tests/functional/test_install_reqs.py
index 40ffc53739de92d9b7098dd58b2f7dbb2e30318b..0454092884f55257d4938a882c7afe07134e6f4f 100644
--- a/tests/functional/test_install_reqs.py
+++ b/tests/functional/test_install_reqs.py
@@ -5,7 +5,7 @@ import pytest
 
 from tests.lib import (
     _create_test_package_with_subdirectory, path_to_url, pyversion,
-    requirements_file
+    requirements_file,
 )
 from tests.lib.local_repos import local_checkout
 
diff --git a/tests/functional/test_install_vcs.py b/tests/functional/test_install_vcs.py
index 4aa27a60b22d9623c8b398f6fca27395bfb61d45..9b3c4a1ddc47094fa5021ee35e38e93cdb3596b6 100644
--- a/tests/functional/test_install_vcs.py
+++ b/tests/functional/test_install_vcs.py
@@ -1,7 +1,7 @@
 import pytest
 
 from tests.lib import (
-    _change_test_package_version, _create_test_package, pyversion
+    _change_test_package_version, _create_test_package, pyversion,
 )
 from tests.lib.local_repos import local_checkout
 
diff --git a/tests/functional/test_install_vcs_git.py b/tests/functional/test_install_vcs_git.py
index e119523e6518fa4905b7b753917eedba07ad4405..f9b5310aecc4390cfe9aa3995e9ddca92bb8e359 100644
--- a/tests/functional/test_install_vcs_git.py
+++ b/tests/functional/test_install_vcs_git.py
@@ -5,7 +5,7 @@ from pip._internal.vcs.git import Git
 from tests.lib import _create_test_package
 from tests.lib.git_submodule_helpers import (
     _change_test_package_submodule, _create_test_package_with_submodule,
-    _pull_in_submodule_changes_to_module
+    _pull_in_submodule_changes_to_module,
 )
 
 
diff --git a/tests/functional/test_search.py b/tests/functional/test_search.py
index 18f7f97f36ed8fa3535b34e693f716cf2635b289..1341a25248e659d696274f7007e16b39fe16e5e8 100644
--- a/tests/functional/test_search.py
+++ b/tests/functional/test_search.py
@@ -1,7 +1,7 @@
 import pytest
 
 from pip._internal.commands.search import (
-    SearchCommand, highest_version, print_results, transform_hits
+    SearchCommand, highest_version, print_results, transform_hits,
 )
 from pip._internal.status_codes import NO_MATCHES_FOUND, SUCCESS
 from tests.lib import pyversion
diff --git a/tests/unit/test_compat.py b/tests/unit/test_compat.py
index 5200fa252aa611f50c41811f66a9ddb4a9d1f3e4..71d3d57626723dff042231340d951a8e3c89d8b9 100644
--- a/tests/unit/test_compat.py
+++ b/tests/unit/test_compat.py
@@ -5,7 +5,7 @@ import pytest
 
 import pip._internal.compat
 from pip._internal.compat import (
-    console_to_str, expanduser, get_path_uid, native_str
+    console_to_str, expanduser, get_path_uid, native_str,
 )
 
 
diff --git a/tests/unit/test_configuration.py b/tests/unit/test_configuration.py
index 815b3c5e4d762fdb01c7925ed4aeeb72ec3ca7fa..ef1ddf96a25d8ee457108ccd3603704006aa2794 100644
--- a/tests/unit/test_configuration.py
+++ b/tests/unit/test_configuration.py
@@ -8,7 +8,7 @@ from mock import MagicMock
 
 from pip._internal.exceptions import ConfigurationError
 from pip._internal.locations import (
-    new_config_file, site_config_files, venv_config_file
+    new_config_file, site_config_files, venv_config_file,
 )
 from tests.lib.configuration_helpers import ConfigurationMixin, kinds
 
diff --git a/tests/unit/test_download.py b/tests/unit/test_download.py
index 29be1396853dd7028dd898db5e535e99ecec57e6..bc6d14b60ddc8db191f63d451bfc64d8e0ee1532 100644
--- a/tests/unit/test_download.py
+++ b/tests/unit/test_download.py
@@ -11,7 +11,7 @@ from pip._vendor.six.moves.urllib import request as urllib_request
 import pip
 from pip._internal.download import (
     MultiDomainBasicAuth, PipSession, SafeFileCache, path_to_url,
-    unpack_file_url, unpack_http_url, url_to_path
+    unpack_file_url, unpack_http_url, url_to_path,
 )
 from pip._internal.exceptions import HashMismatch
 from pip._internal.index import Link
diff --git a/tests/unit/test_finder.py b/tests/unit/test_finder.py
index c909518b2f9b550ebe115ddae7d2b29196ee44d4..5188e3eb23deed2aa486a042069d72c41c1dc18f 100644
--- a/tests/unit/test_finder.py
+++ b/tests/unit/test_finder.py
@@ -8,10 +8,10 @@ import pip._internal.pep425tags
 import pip._internal.wheel
 from pip._internal.download import PipSession
 from pip._internal.exceptions import (
-    BestVersionAlreadyInstalled, DistributionNotFound
+    BestVersionAlreadyInstalled, DistributionNotFound,
 )
 from pip._internal.index import (
-    FormatControl, InstallationCandidate, Link, PackageFinder, fmt_ctl_formats
+    FormatControl, InstallationCandidate, Link, PackageFinder, fmt_ctl_formats,
 )
 from pip._internal.req import InstallRequirement
 
diff --git a/tests/unit/test_req.py b/tests/unit/test_req.py
index 1e4646cd54a51f131d35fc01433a58e87a394d57..9ef6927308b727bd43d32743bb520d69e6795dfa 100644
--- a/tests/unit/test_req.py
+++ b/tests/unit/test_req.py
@@ -12,7 +12,7 @@ from pip._vendor.packaging.requirements import Requirement
 from pip._internal.commands.install import InstallCommand
 from pip._internal.download import PipSession, path_to_url
 from pip._internal.exceptions import (
-    HashErrors, InstallationError, InvalidWheelFilename, PreviousBuildDirError
+    HashErrors, InstallationError, InvalidWheelFilename, PreviousBuildDirError,
 )
 from pip._internal.index import PackageFinder
 from pip._internal.operations.prepare import RequirementPreparer
diff --git a/tests/unit/test_req_file.py b/tests/unit/test_req_file.py
index 8b83b641c2977f88ef70799b4efa15318a66e85f..2f04c1599afb383354e4ee4646d559899f05753a 100644
--- a/tests/unit/test_req_file.py
+++ b/tests/unit/test_req_file.py
@@ -9,12 +9,12 @@ from pretend import stub
 import pip._internal.index
 from pip._internal.download import PipSession
 from pip._internal.exceptions import (
-    InstallationError, RequirementsFileParseError
+    InstallationError, RequirementsFileParseError,
 )
 from pip._internal.index import PackageFinder
 from pip._internal.req.req_file import (
     break_args_options, ignore_comments, join_lines, parse_requirements,
-    preprocess, process_line, skip_regex
+    preprocess, process_line, skip_regex,
 )
 from pip._internal.req.req_install import InstallRequirement
 from tests.lib import requirements_file
diff --git a/tests/unit/test_req_uninstall.py b/tests/unit/test_req_uninstall.py
index af8176ba4a325129419f9b543c3886525d37e796..6756046a1ed833f9c850f12c453d85d8e1ed1692 100644
--- a/tests/unit/test_req_uninstall.py
+++ b/tests/unit/test_req_uninstall.py
@@ -6,7 +6,7 @@ from mock import Mock
 import pip._internal.req.req_uninstall
 from pip._internal.req.req_uninstall import (
     UninstallPathSet, compact, compress_for_output_listing,
-    uninstallation_paths
+    uninstallation_paths,
 )
 from tests.lib import create_file
 
diff --git a/tests/unit/test_utils.py b/tests/unit/test_utils.py
index acfa6193ae30bcb944df62a582693d1fe7c55a8e..cdd76ccfcd7edb8cba11d41f4063875671abbaf9 100644
--- a/tests/unit/test_utils.py
+++ b/tests/unit/test_utils.py
@@ -17,14 +17,14 @@ from mock import Mock, patch
 from pip._vendor.six import BytesIO
 
 from pip._internal.exceptions import (
-    HashMismatch, HashMissing, InstallationError, UnsupportedPythonVersion
+    HashMismatch, HashMissing, InstallationError, UnsupportedPythonVersion,
 )
 from pip._internal.utils.encoding import auto_decode
 from pip._internal.utils.glibc import check_glibc_version
 from pip._internal.utils.hashes import Hashes, MissingHashes
 from pip._internal.utils.misc import (
     egg_link_path, ensure_dir, get_installed_distributions, get_prog,
-    normalize_path, rmtree, untar_file, unzip_file
+    normalize_path, rmtree, untar_file, unzip_file,
 )
 from pip._internal.utils.packaging import check_dist_requires_python
 from pip._internal.utils.temp_dir import TempDirectory