Fixed #23652 -- Restored database name after destroying test database

Thanks Bjarkias for the report.

django/db/backends/creation.py

@@ -524,6 +524,10 @@ class BaseDatabaseCreation(object):
         if not keepdb:
             self._destroy_test_db(test_database_name, verbosity)
 
+        # Restore the original database name
+        settings.DATABASES[self.connection.alias]["NAME"] = old_database_name
+        self.connection.settings_dict["NAME"] = old_database_name
+
     def _destroy_test_db(self, test_database_name, verbosity):
         """
         Internal implementation - remove the test db tables.

tests/test_runner/tests.py

@@ -6,6 +6,7 @@ from __future__ import unicode_literals
 import unittest
 
 from django import db
+from django.conf import settings
 from django.core.exceptions import ImproperlyConfigured
 from django.core.management import call_command
 from django.db.backends.dummy.base import DatabaseCreation
@@ -336,6 +337,18 @@ class SetupDatabasesTests(unittest.TestCase):
 
         self.assertEqual(destroyed_names.count('dbname'), 1)
 
+    def test_destroy_test_db_restores_db_name(self):
+        db.connections = db.ConnectionHandler({
+            'default': {
+                'ENGINE': settings.DATABASES[db.DEFAULT_DB_ALIAS]["ENGINE"],
+                'NAME': 'xxx_test_database',
+            },
+        })
+        # Using the real current name as old_name to not mess with the test suite.
+        old_name = settings.DATABASES[db.DEFAULT_DB_ALIAS]["NAME"]
+        db.connections['default'].creation.destroy_test_db(old_name, verbosity=0, keepdb=True)
+        self.assertEqual(db.connections['default'].settings_dict["NAME"], old_name)
+
     def test_serialization(self):
         serialize = []
         DatabaseCreation.create_test_db = (