Commits
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7a8e1b3 ChoiceType flattens nested Choices when expanded
82b0b37 Added ChoiceType test for flattening grouped Choices when expanded
Discussion
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Fixed#2545 - ChoiceType flattens grouped Choices when expanded
Bug fix: yes
Feature addition: no
Backwards compatibility break: no
Symfony2 tests pass: yes
Fixes the following tickets: #2545
**Problem**: With PR #2464, a bug was discovered when nested choices threw a exception during rendering.
**Solution**: Nested choices are flattened prior to creating checkbox/radio fields.