Deprecate loading ssi/url tags from future

[Tim Graham]

In #18037, it was decided to add this to the deprecation timeline under 2.0: "ssi and url template tags will be removed from the future template tag library (used during the 1.3/1.4 deprecation period)."

At this time, it appears unlikely (from the discussion I've come across) that Django will have a "2.0" in the sense of a major backwards incompatible release in the foreseeable future. Thus, I think having this on the deprecation timeline may create some confusion. If we want to keep it, I think we should at least add some clarifying text as to what "2.0" means.

[Aymeric Augustin]

I think 2.0 is simply the version after 1.9. Unless someone says otherwise, this is going to happen ;-)

[Claude Paroz]

We might also choose 2.0 as the Django version where we drop Python 2 support.

[Aymeric Augustin]

There would be no 1.9 then ;-)

[Jannis Leidel]

Looking back at the ticket I have to say, I think I still believed that a Django 2.0 would eventually be a API breaking release as Python 3. Now that we know how hostile that has been to Python I think we should reconsider this and use a proper deprecation roadmap.

I also would rather not use those poor template tags for creating a precedence of deciding what 2.0 means -- it's a much bigger discussion and shouldn't bound to bad decisions of the past. Let's move the deprecation into 1.9 and be done with it.

[Tim Graham]

@jezdez -- sounds good to me. Should be relatively "easy pickings" by following the ​deprecating a feature guide.

[Zbigniew Siciarz]

The note at ​https://docs.djangoproject.com/en/dev/intro/tutorial03/#removing-hardcoded-urls-in-templates is mentioning Django < 1.5, is it worth keeping it?

[Tim Graham]

We can remove that note. The latest version of the tutorial isn't designed to support multiple versions.

[Zbigniew Siciarz]

Deprecated, relevant PR: ​https://github.com/django/django/pull/2308

[Zbigniew Siciarz <antyqjon@…>]

In 74d4d58b62f3a68bf77b983bc8a475a130d1f95e:

Fixed #21939 -- Deprecated loading ssi/url tags from future.

[Tim Graham <timograham@…>]

In bd93032191f96bc7086aa46b91b4177601c6fce9:

Removed ssi/url tags from future per deprecation timeline; refs #21939.