[1.4.x] Fixed SQLite's collapsing of same-valued instances in bulk_create

SQLite used INSERT INTO tbl SELECT %s UNION SELECT %s, the problem
was that there should have been UNION ALL instead of UNION.

Refs #19351

Backpatch of a27582484cf814554907d2d1ad077852de36963f
[1.4.x] Restored Python 2.5 compatibility in m2m_through_regress tests.

Refs #18823.
[1.4.x] Fixed ordering-related failure in m2m_through_regress tests

Backpatch of dc569c880143db07e01b3293d698ad8fe4a0136f
[1.4.x] Fixed #19318 -- Ensured that the admin's SimpleListFilter options can be displayed as selected even if the lookup's first element is not a string.
Backport of 88e17156393b
[1.4.x] Fixed the admin_filters tests for Postgres.
Backport of c196e01100b2
[1.4.X] Fixed #18856 -- Ensured that redirects can't be poisoned by malicious users.
[1.4.X] Fixed a security issue in get_host.

Full disclosure and new release forthcoming.
[1.4.x] Bump version numbers for security release.
[1.4.X] Fixed a test failure in the comment tests.

Backport of 1eb0da1c5ba3096f218d1df13d02a2b8e1ac7a36 from master.
[1.4.X] Fixed #18099 -- corrected a typo in the initial data docs.  Thanks to Bradley Ayers for the patch.

Backport of f5a9e5e9 from master
[1.4.x] Added PASSWORD_HASHERS to settings reference document.

abd0f304b162b3120b1c7321fbfc3090e5f3c92c from master.
[1.4.X] Fixed #19506 - Remove 'mysite' prefix in model example.

Thanks Mike O'Connor for the report.

Backport of 52a2588df6 from master
[1.4.x] Addeded CSS to bold deprecation notices.

Thanks Sam Lai for mentioning this on the mailing list.

Backport of 227bd3f8db from master