[2.2.x] Fixed a failure when running tests on systems with SQLite < 3.8.3.

Backport of 36300ef336 from master.

tests/backends/sqlite/tests.py

@@ -6,7 +6,6 @@ from unittest import mock
 
 from django.core.exceptions import ImproperlyConfigured
 from django.db import connection, transaction
-from django.db.backends.sqlite3.base import check_sqlite_version
 from django.db.models import Avg, StdDev, Sum, Variance
 from django.db.models.aggregates import Aggregate
 from django.db.models.fields import CharField
@@ -18,6 +17,12 @@ from django.test.utils import isolate_apps
 
 from ..models import Author, Item, Object, Square
 
+try:
+    from django.db.backends.sqlite3.base import check_sqlite_version
+except ImproperlyConfigured:
+    # Ignore "SQLite is too old" when running tests on another database.
+    pass
+
 
 @unittest.skipUnless(connection.vendor == 'sqlite', 'SQLite tests')
 class Tests(TestCase):