Normalized check that ALLOWED_INCLUDE_ROOTS is a tuple.

django/conf/__init__.py

@@ -74,9 +74,6 @@ class BaseSettings(object):
     def __setattr__(self, name, value):
         if name in ("MEDIA_URL", "STATIC_URL") and value and not value.endswith('/'):
             raise ImproperlyConfigured("If set, %s must end with a slash" % name)
-        elif name == "ALLOWED_INCLUDE_ROOTS" and isinstance(value, six.string_types):
-            raise ValueError("The ALLOWED_INCLUDE_ROOTS setting must be set "
-                "to a tuple, not a string.")
         object.__setattr__(self, name, value)
 
 
@@ -92,7 +89,12 @@ class Settings(BaseSettings):
 
         mod = importlib.import_module(self.SETTINGS_MODULE)
 
-        tuple_settings = ("INSTALLED_APPS", "TEMPLATE_DIRS", "LOCALE_PATHS")
+        tuple_settings = (
+            "ALLOWED_INCLUDE_ROOTS",
+            "INSTALLED_APPS",
+            "TEMPLATE_DIRS",
+            "LOCALE_PATHS",
+        )
         self._explicit_settings = set()
         for setting in dir(mod):
             if setting.isupper():