[2.1.x] Reverted "Fixed #29324 -- Made Settings raise ImproperlyConfigured if SECRET_KEY is accessed and not set."

This reverts commit b3cffde5559c4fa97625512d7ec41a674be26076 due to
a regression and performance concerns.

Backport of 5cc81cd9eb69f5f7a711412c02039b435c393135 from master

2 files changed, 8 insertions, 8 deletions

diff --git a/django/conf/__init__.py b/django/conf/__init__.py
index 9b3e350a50..05c603786e 100644
--- a/django/conf/__init__.py
+++ b/django/conf/__init__.py
@@ -116,15 +116,15 @@ class Settings:
             if setting.isupper():
                 setting_value = getattr(mod, setting)
 
-                if setting == 'SECRET_KEY' and not setting_value:
-                    raise ImproperlyConfigured('The SECRET_KEY setting must not be empty.')
-
                 if (setting in tuple_settings and
                         not isinstance(setting_value, (list, tuple))):
                     raise ImproperlyConfigured("The %s setting must be a list or a tuple. " % setting)
                 setattr(self, setting, setting_value)
                 self._explicit_settings.add(setting)
 
+        if not self.SECRET_KEY:
+            raise ImproperlyConfigured("The SECRET_KEY setting must not be empty.")
+
         if self.is_overridden('DEFAULT_CONTENT_TYPE'):
             warnings.warn('The DEFAULT_CONTENT_TYPE setting is deprecated.', RemovedInDjango30Warning)
 
@@ -140,11 +140,6 @@ class Settings:
             os.environ['TZ'] = self.TIME_ZONE
             time.tzset()
 
-    def __getattr__(self, name):
-        if name == 'SECRET_KEY':
-            raise ImproperlyConfigured('The SECRET_KEY setting must be set.')
-        raise AttributeError("'%s' object has no attribute '%s'" % (self.__class__.__name__, name))
-
     def is_overridden(self, setting):
         return setting in self._explicit_settings
 
diff --git a/django/conf/global_settings.py b/django/conf/global_settings.py
index 26fa492892..befade160f 100644
--- a/django/conf/global_settings.py
+++ b/django/conf/global_settings.py
@@ -256,6 +256,11 @@ ABSOLUTE_URL_OVERRIDES = {}
 #    ]
 IGNORABLE_404_URLS = []
 
+# A secret key for this particular Django installation. Used in secret-key
+# hashing algorithms. Set this in your settings, or Django will complain
+# loudly.
+SECRET_KEY = ''
+
 # Default file storage mechanism that holds media.
 DEFAULT_FILE_STORAGE = 'django.core.files.storage.FileSystemStorage'