Fixed #15112 -- Ensure that IPv6 addresses are correctly displayed in the...

Fixed #15112 -- Ensure that IPv6 addresses are correctly displayed in the admin. Thanks to oxy for the report, and Łukasz Rekucki for the test case.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@15343 bcc190cf-cafb-0310-a4f2-bffc1f526a37