bug symfony#26254 fix custom radios/inputs for checkbox/radio type (mssimi)

This PR was merged into the 3.4 branch.

Discussion
----------

fix custom radios/inputs for checkbox/radio type

| Q             | A
| ------------- | ---
| Branch?       | 3.4
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   |
| Fixed tickets | symfony#25715
| License       | MIT
| Doc PR        |

Hey, I tried new changes in bootstrap 4 layout. Unfortunatelly custom-radios/checkboxes seems to work only for ChoiceType/EntityType but not for CheckboxType/RadioType. I added changes which I belive fix this issue.

Commits
-------

dd6d1dd fix custom radios/inputs for checkbox/radio type

Author: fabpot

src/Symfony/Bridge/Twig/Resources/views/Form/bootstrap_4_layout.html.twig

@@ -190,7 +190,9 @@
 {% block checkbox_radio_label -%}
     {#- Do not display the label if widget is not defined in order to prevent double label rendering -#}
     {%- if widget is defined -%}
-        {%- if parent_label_class is defined and ('checkbox-custom' in parent_label_class or 'radio-custom' in parent_label_class) -%}
+        {% set is_parent_custom = parent_label_class is defined and ('checkbox-custom' in parent_label_class or 'radio-custom' in parent_label_class) %}
+        {% set is_custom = label_attr.class is defined and ('checkbox-custom' in label_attr.class or 'radio-custom' in label_attr.class) %}
+        {%- if is_parent_custom or is_custom -%}
             {%- set label_attr = label_attr|merge({class: (label_attr.class|default('') ~ ' custom-control-label')|trim}) -%}
         {%- else %}
             {%- set label_attr = label_attr|merge({class: (label_attr.class|default('') ~ ' form-check-label')|trim}) -%}