Reverted "Fixed #27818 -- Replaced try/except/pass with contextlib.suppress()."

This reverts commit 550cb3a365dee4edfdd1563224d5304de2a57fda
because try/except performs better.

9 files changed, 61 insertions, 38 deletions

diff --git a/django/core/cache/backends/filebased.py b/django/core/cache/backends/filebased.py
index deceffaa0d..dccc3fdc65 100644
--- a/django/core/cache/backends/filebased.py
+++ b/django/core/cache/backends/filebased.py
@@ -7,7 +7,6 @@ import random
 import tempfile
 import time
 import zlib
-from contextlib import suppress
 
 from django.core.cache.backends.base import DEFAULT_TIMEOUT, BaseCache
 from django.core.files.move import file_move_safe
@@ -30,10 +29,12 @@ class FileBasedCache(BaseCache):
 
     def get(self, key, default=None, version=None):
         fname = self._key_to_file(key, version)
-        with suppress(FileNotFoundError):
+        try:
             with open(fname, 'rb') as f:
                 if not self._is_expired(f):
                     return pickle.loads(zlib.decompress(f.read()))
+        except FileNotFoundError:
+            pass
         return default
 
     def set(self, key, value, timeout=DEFAULT_TIMEOUT, version=None):
@@ -59,9 +60,11 @@ class FileBasedCache(BaseCache):
     def _delete(self, fname):
         if not fname.startswith(self._dir) or not os.path.exists(fname):
             return
-        with suppress(FileNotFoundError):
-            # The file may have been removed by another process.
+        try:
             os.remove(fname)
+        except FileNotFoundError:
+            # The file may have been removed by another process.
+            pass
 
     def has_key(self, key, version=None):
         fname = self._key_to_file(key, version)
@@ -90,8 +93,10 @@ class FileBasedCache(BaseCache):
 
     def _createdir(self):
         if not os.path.exists(self._dir):
-            with suppress(FileExistsError):
+            try:
                 os.makedirs(self._dir, 0o700)
+            except FileExistsError:
+                pass
 
     def _key_to_file(self, key, version=None):
         """
diff --git a/django/core/cache/backends/locmem.py b/django/core/cache/backends/locmem.py
index 20b6dd4212..b2600d3169 100644
--- a/django/core/cache/backends/locmem.py
+++ b/django/core/cache/backends/locmem.py
@@ -1,7 +1,7 @@
 "Thread-safe in-memory cache backend."
 import pickle
 import time
-from contextlib import contextmanager, suppress
+from contextlib import contextmanager
 
 from django.core.cache.backends.base import DEFAULT_TIMEOUT, BaseCache
 from django.utils.synch import RWLock
@@ -50,9 +50,11 @@ class LocMemCache(BaseCache):
                 return default
 
         with (self._lock.writer() if acquire_lock else dummy()):
-            with suppress(KeyError):
+            try:
                 del self._cache[key]
                 del self._expire_info[key]
+            except KeyError:
+                pass
             return default
 
     def _set(self, key, value, timeout=DEFAULT_TIMEOUT):
@@ -87,9 +89,11 @@ class LocMemCache(BaseCache):
                 return True
 
         with self._lock.writer():
-            with suppress(KeyError):
+            try:
                 del self._cache[key]
                 del self._expire_info[key]
+            except KeyError:
+                pass
             return False
 
     def _has_expired(self, key):
@@ -107,11 +111,14 @@ class LocMemCache(BaseCache):
                 self._delete(k)
 
     def _delete(self, key):
-        with suppress(KeyError):
+        try:
             del self._cache[key]
-
-        with suppress(KeyError):
+        except KeyError:
+            pass
+        try:
             del self._expire_info[key]
+        except KeyError:
+            pass
 
     def delete(self, key, version=None):
         key = self.make_key(key, version=version)
diff --git a/django/core/files/move.py b/django/core/files/move.py
index 310e064a2d..4d791ac263 100644
--- a/django/core/files/move.py
+++ b/django/core/files/move.py
@@ -7,7 +7,6 @@ Move a file in the safest way possible::
 
 import errno
 import os
-from contextlib import suppress
 from shutil import copystat
 
 from django.core.files import locks
@@ -42,14 +41,16 @@ def file_move_safe(old_file_name, new_file_name, chunk_size=1024 * 64, allow_ove
     if _samefile(old_file_name, new_file_name):
         return
 
-    # OSError happens with os.rename() if moving to another filesystem or when
-    # moving opened files on certain operating systems.
-    with suppress(OSError):
+    try:
         if not allow_overwrite and os.access(new_file_name, os.F_OK):
             raise IOError("Destination file %s exists and allow_overwrite is False" % new_file_name)
 
         os.rename(old_file_name, new_file_name)
         return
+    except OSError:
+        # OSError happens with os.rename() if moving to another filesystem or
+        # when moving opened files on certain operating systems.
+        pass
 
     # first open the old file, so that it won't go away
     with open(old_file_name, 'rb') as old_file:
diff --git a/django/core/files/storage.py b/django/core/files/storage.py
index fa98bb198a..30788d6d75 100644
--- a/django/core/files/storage.py
+++ b/django/core/files/storage.py
@@ -1,5 +1,4 @@
 import os
-from contextlib import suppress
 from datetime import datetime
 from urllib.parse import urljoin
 
@@ -224,10 +223,7 @@ class FileSystemStorage(Storage):
         # Create any intermediate directories that do not exist.
         directory = os.path.dirname(full_path)
         if not os.path.exists(directory):
-            # There's a race between os.path.exists() and os.makedirs().
-            # If os.makedirs() fails with FileNotFoundError, the directory
-            # was created concurrently.
-            with suppress(FileNotFoundError):
+            try:
                 if self.directory_permissions_mode is not None:
                     # os.makedirs applies the global umask, so we reset it,
                     # for consistency with file_permissions_mode behavior.
@@ -238,6 +234,11 @@ class FileSystemStorage(Storage):
                         os.umask(old_umask)
                 else:
                     os.makedirs(directory)
+            except FileNotFoundError:
+                # There's a race between os.path.exists() and os.makedirs().
+                # If os.makedirs() fails with FileNotFoundError, the directory
+                # was created concurrently.
+                pass
         if not os.path.isdir(directory):
             raise IOError("%s exists and is not a directory." % directory)
 
@@ -293,13 +294,15 @@ class FileSystemStorage(Storage):
         assert name, "The name argument is not allowed to be empty."
         name = self.path(name)
         # If the file or directory exists, delete it from the filesystem.
-        # FileNotFoundError is raised if the file or directory was removed
-        # concurrently.
-        with suppress(FileNotFoundError):
+        try:
             if os.path.isdir(name):
                 os.rmdir(name)
             else:
                 os.remove(name)
+        except FileNotFoundError:
+            # FileNotFoundError is raised if the file or directory was removed
+            # concurrently.
+            pass
 
     def exists(self, name):
         return os.path.exists(self.path(name))
diff --git a/django/core/management/__init__.py b/django/core/management/__init__.py
index b68692d60a..77c060c21c 100644
--- a/django/core/management/__init__.py
+++ b/django/core/management/__init__.py
@@ -3,7 +3,6 @@ import os
 import pkgutil
 import sys
 from collections import OrderedDict, defaultdict
-from contextlib import suppress
 from importlib import import_module
 
 import django
@@ -262,12 +261,14 @@ class ManagementUtility:
             subcommand_cls = self.fetch_command(cwords[0])
             # special case: add the names of installed apps to options
             if cwords[0] in ('dumpdata', 'sqlmigrate', 'sqlsequencereset', 'test'):
-                # Fail silently if DJANGO_SETTINGS_MODULE isn't set. The
-                # user will find out once they execute the command.
-                with suppress(ImportError):
+                try:
                     app_configs = apps.get_app_configs()
                     # Get the last part of the dotted path as the app name.
                     options.extend((app_config.label, 0) for app_config in app_configs)
+                except ImportError:
+                    # Fail silently if DJANGO_SETTINGS_MODULE isn't set. The
+                    # user will find out once they execute the command.
+                    pass
             parser = subcommand_cls.create_parser('', cwords[0])
             options.extend(
                 (min(s_opt.option_strings), s_opt.nargs != 0)
@@ -306,9 +307,11 @@ class ManagementUtility:
         parser.add_argument('--settings')
         parser.add_argument('--pythonpath')
         parser.add_argument('args', nargs='*')  # catch-all
-        with suppress(CommandError):  # Ignore any option errors at this point.
+        try:
             options, args = parser.parse_known_args(self.argv[2:])
             handle_default_options(options)
+        except CommandError:
+            pass  # Ignore any option errors at this point.
 
         try:
             settings.INSTALLED_APPS
diff --git a/django/core/management/base.py b/django/core/management/base.py
index b53b414fdb..41b6b0fa91 100644
--- a/django/core/management/base.py
+++ b/django/core/management/base.py
@@ -5,7 +5,6 @@ be executed through ``django-admin`` or ``manage.py``).
 import os
 import sys
 from argparse import ArgumentParser
-from contextlib import suppress
 from io import TextIOBase
 
 import django
@@ -298,10 +297,12 @@ class BaseCommand:
                 self.stderr.write('%s: %s' % (e.__class__.__name__, e))
             sys.exit(1)
         finally:
-            # Ignore if connections aren't setup at this point (e.g. no
-            # configured settings).
-            with suppress(ImproperlyConfigured):
+            try:
                 connections.close_all()
+            except ImproperlyConfigured:
+                # Ignore if connections aren't setup at this point (e.g. no
+                # configured settings).
+                pass
 
     def execute(self, *args, **options):
         """
diff --git a/django/core/management/commands/flush.py b/django/core/management/commands/flush.py
index 0df5f67e39..f6ae83940a 100644
--- a/django/core/management/commands/flush.py
+++ b/django/core/management/commands/flush.py
@@ -1,4 +1,3 @@
-from contextlib import suppress
 from importlib import import_module
 
 from django.apps import apps
@@ -40,8 +39,10 @@ class Command(BaseCommand):
         # Import the 'management' module within each installed app, to register
         # dispatcher events.
         for app_config in apps.get_app_configs():
-            with suppress(ImportError):
+            try:
                 import_module('.management', app_config.name)
+            except ImportError:
+                pass
 
         sql_list = sql_flush(self.style, connection, only_django=True,
                              reset_sequences=reset_sequences,
diff --git a/django/core/management/commands/shell.py b/django/core/management/commands/shell.py
index ce013bcec0..7c9a43434a 100644
--- a/django/core/management/commands/shell.py
+++ b/django/core/management/commands/shell.py
@@ -2,7 +2,6 @@ import os
 import select
 import sys
 import traceback
-from contextlib import suppress
 
 from django.core.management import BaseCommand, CommandError
 from django.utils.datastructures import OrderedSet
@@ -96,6 +95,8 @@ class Command(BaseCommand):
         available_shells = [options['interface']] if options['interface'] else self.shells
 
         for shell in available_shells:
-            with suppress(ImportError):
+            try:
                 return getattr(self, shell)(options)
+            except ImportError:
+                pass
         raise CommandError("Couldn't import {} interface.".format(shell))
diff --git a/django/core/validators.py b/django/core/validators.py
index c6d5e6e06a..b36ab60704 100644
--- a/django/core/validators.py
+++ b/django/core/validators.py
@@ -1,7 +1,6 @@
 import ipaddress
 import os
 import re
-from contextlib import suppress
 from urllib.parse import urlsplit, urlunsplit
 
 from django.core.exceptions import ValidationError
@@ -215,9 +214,11 @@ class EmailValidator:
         literal_match = self.literal_regex.match(domain_part)
         if literal_match:
             ip_address = literal_match.group(1)
-            with suppress(ValidationError):
+            try:
                 validate_ipv46_address(ip_address)
                 return True
+            except ValidationError:
+                pass
         return False
 
     def __eq__(self, other):