url tag urlencodes arguments irreversibly

[leo@…]

Somewhere between 1.4 and 1.6 the url tag started urlencoding arguments before outputing the URL. This breaks code that wants to build the url inside javascript in the following way:

<script>
  var url = '{% url "some_view" "'+some_js_argument+'" %}'
</script>

On 1.4 this generates '/some/view/'+some_js_argument+'/'
On 1.6 this generates '/some/view/%27%2Bsome_js_argument%2B%27'

While I understand the rationale behind urlencoding per default, it would be nice to provide a way to avoid it. "|safe" seems to have no effect and even a custom filter to urldecode the output doesn't help, since urlencoding seems to be the last step before output.
Please consider providing a way to disable this, either by filter or by options to the url tag, so that we're not forced to use kludgy workarounds like

<script>
  var url = '{% url "some_view" "ARGUMENT_BY_JS" %}'.replace(/ARGUMENT_BY_JS/, some_js_argument)
</script>

Additionally, this might be a good thing to mention in the docs.

This is admittedly somewhere between a bug and a feature request, but since this breaks old code, I've decided to submit it as a regression bug.

[Florian Apolloner]

I think the url tag should always return proper URLs, but we should document it clearly.

[Tim Graham]

For the record, this was ​introduced in Django 1.6.

[Tim Graham <timograham@…>]

In dfc092622e5e55081f9a76fddea752494c4505ba:

Fixed #21529 -- Noted that {% url %} encodes its output (refs #13260).

[Tim Graham <timograham@…>]

In a4c32d70c2bcf9731b6d6ff3370d2260ab4812af:

[1.6.x] Fixed #21529 -- Noted that {% url %} encodes its output (refs #13260).

Backport of dfc092622e from master