Template widget rendering: attrs with value False now render

[Jon Dufresne]

In Django 1.10, widget attrs with a value of False do not render. See the code: ​https://github.com/django/django/blob/stable/1.10.x/django/forms/utils.py#L40-L42

In Django 1.11, these attributes now render as ="False". This is because the ​attrs.html template only looks for the boolean value True.

This forces code of the form:

attrs['readonly'] = some_bool_condition()

To:

if some_bool_condition():
    attrs['readonly'] = True

[Jon Dufresne]

​PR

[Jon Dufresne]

Added test.

[Tim Graham <timograham@…>]

In 5fa390e:

Fixed #27759 -- Prevented forms attrs.html template from rendering False attrs.

Regression in b52c73008a9d67e9ddbb841872dc15cdd3d6ee01.

[Tim Graham <timograham@…>]

In 9e9d0f8:

[1.11.x] Fixed #27759 -- Prevented forms attrs.html template from rendering False attrs.

Regression in b52c73008a9d67e9ddbb841872dc15cdd3d6ee01.

Backport of 5fa390ee81c5a963fc4476e8de6c1e5e1fc57e22 from master