Symfony Form's nested form + FormEvents::POST_SET_DATA reproducer

Installation

  1. composer install
  2. Set up your .env.local and hook it up with a local MySQL installation
  3. symfony doctrine:migrations:migrate to get some test data
  4. Setup a webserver to run this app

Reproducer

  1. Go to / to find a super fancy index page that presents you with two links: One to the working form and another to the broken. Click on either link
  2. Note the web debug toolbar is dumping EntityA
  3. Note that, depending on which form you're currently working on, the EntityB dropdown is either pre-selected or empty!