bug symfony#24711 [TwigBridge] Re-add Bootstrap 3 Checkbox Layout (arkste)

This PR was merged into the 3.4 branch.

Discussion
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[TwigBridge] Re-add Bootstrap 3 Checkbox Layout

| Q             | A
| ------------- | ---
| Branch?       | 3.4
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | symfony#24702
| License       | MIT
| Doc PR        |

Commits
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8ac8f9d [TwigBridge] Re-add Bootstrap 3 Checkbox Layout

Author: nicolas-grekas

src/Symfony/Bridge/Twig/Resources/views/Form/bootstrap_3_layout.html.twig

@@ -123,10 +123,15 @@
 {%- endblock datetime_row %}
 
 {% block checkbox_row -%}
+{% spaceless %}
     <div class="form-group{% if not valid %} has-error{% endif %}">
-        {{- form_widget(form) -}}
-        {{- form_errors(form) -}}
+        <div class="{{ block('form_label_class') }}"></div>
+        <div class="{{ block('form_group_class') }}">
+            {{- form_widget(form) -}}
+            {{- form_errors(form) -}}
+        </div>
     </div>
+{% endspaceless %}
 {%- endblock checkbox_row %}
 
 {% block radio_row -%}