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Changes between Version 2 and Version 3 of Ticket #29721, comment 12

-              v2
+              v3
 After #32374, the bug still happens for migrations that use deferred sql (which is a lot, like CreateModel, AlterField...). Maybe BaseDatabaseSchemaEditor needs to take a record_migration callback so it can always be recorded in the atomic block? The deferred_sql check was kind of deeply coupled.
 I believe the most realistic and reliable reproducible reproducer is to add `import os; os.kill(os.getpid(), 9)  # simulate an hard crash during migration recording.` to the first line of record_migration. A unrecoverable hard crash can happen at any time, that's why we have transactions.
+I believe the most realistic and reliable reproducible reproducer is to simulate a hard crash during migration recording by adding `import os; os.kill(os.getpid(), 9)` or `import sys; sys.exit()` to the first line of BaseDatabaseSchemaEditor.record_migration. A unrecoverable hard crash can happen at any time, that's why we have transactions.
 I've reproduced the issue with a deferred_sql migration and tested this fix
 …
 }}}
+Minimal model to get deferred_sql:
+{{{#!python
+from django.db import models
+class Foo(models.Model):
+    a = models.ForeignKey('self', on_delete=models.CASCADE)
+}}}