bug #31972 Add missing rendering of form help block. (alexsegura)
bug #31972 Add missing rendering of form help block. (alexsegura)

This PR was merged into the 4.2 branch.

Discussion
----------

Add missing rendering of form help block.

| Q             | A
| ------------- | ---
| Branch?       | 4.2 <!-- see below -->
| Bug fix?      | yes
| New feature?  | no <!-- please update src/**/CHANGELOG.md files -->
| BC breaks?    | no     <!-- see https://symfony.com/bc -->
| Deprecations? | no <!-- please update UPGRADE-*.md and src/**/CHANGELOG.md files -->
| Tests pass?   | yes    <!-- please add some, will be required by reviewers -->
| License       | MIT

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 - Bug fixes must be submitted against the lowest maintained branch where they apply
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When using `bootstrap_3_layout.html.twig` form theme, the help blocks are not rendered.

```twig
{% form_theme form 'bootstrap_3_layout.html.twig' %}

{{ form_start(form) }}
  {{ form_row(form.some_field) }} {# <-- no help text is rendered #}
{{ form_end(form) }}
```

Commits
-------

ff5517e554 Add missing rendering of form help block.

symfony/twig-bridge,symfony/TwigBridge