Security update for python-Django1 (important)

This update for python-Django1 to version 1.11.15 fixes the following
issues:

The following security vulnerability was fixed:

• CVE-2018-14574: Fixed an open redirect possibility in CommonMiddleware
  (boo#1102680)

The following other bugs were fixed:

• Fixed WKBWriter.write() and write_hex() for empty polygons on GEOS 3.6.1+
• Fixed a regression where altering a field with a unique constraint may
  drop and rebuild more foreign keys than necessary
• Fixed crashes in django.contrib.admindocs when a view is a callable
  object, such as django.contrib.syndication.views.Feed
• Fixed a regression where QuerySet.values() or values_list() after
  combining an annotated and unannotated queryset with union(),
  difference(), or intersection() crashed due to mismatching columns