Do not try to create revision if current transaction is under rollback.

reversion/revisions.py

@@ -277,6 +277,13 @@ def _create_revision_context(manage_manually, using, atomic):
         _push_frame(manage_manually, using)
         try:
             yield
+            if transaction.get_connection(using).in_atomic_block and transaction.get_rollback(using):
+                # Transaction is in invalid state due to catched exception within yield statement.
+                # Do not try to create Revision, otherwise it would lead to the transaction management error.
+                #
+                # Atomic block could be called manually around `create_revision` context manager.
+                # That's why we have to check connection flag instead of `atomic` variable value.
+                return
             # Only save for a db if that's the last stack frame for that db.
             if not any(using in frame.db_versions for frame in _stack.get()[:-1]):
                 current_frame = _current_frame()

tests/test_app/migrations/0001_initial.py

@@ -108,4 +108,11 @@ class Migration(migrations.Migration):
                 ('revision', models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, to='reversion.revision')),
             ],
         ),
+        migrations.CreateModel(
+            name='TestModelWithUniqueConstraint',
+            fields=[
+                ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
+                ('name', models.CharField(max_length=191, unique=True)),
+            ],
+        ),
     ]

tests/test_app/models.py

@@ -142,3 +142,11 @@ class TestModelInlineByNaturalKey(models.Model):
         TestModelWithNaturalKey,
         on_delete=models.CASCADE,
     )
+
+
+class TestModelWithUniqueConstraint(models.Model):
+
+    name = models.CharField(
+        max_length=191,
+        unique=True,
+    )

tests/test_app/tests/test_models.py

@@ -4,6 +4,7 @@
     TestModel, TestModelRelated, TestModelParent, TestModelInline,
     TestModelNestedInline,
     TestModelInlineByNaturalKey, TestModelWithNaturalKey,
+    TestModelWithUniqueConstraint,
 )
 from test_app.tests.base import TestBase, TestModelMixin, TestModelParentMixin
 import json
@@ -443,3 +444,17 @@ def testNaturalKeyInline(self):
             'test_model_id': 1,
             'id': 1,
         })
+
+
+class TransactionRollbackTest(TestBase):
+
+    def setUp(self):
+        reversion.register(TestModelWithUniqueConstraint)
+
+    def testTransactionInRollbackState(self):
+        with reversion.create_revision():
+            try:
+                TestModelWithUniqueConstraint.objects.create(name='A')
+                TestModelWithUniqueConstraint.objects.create(name='A')
+            except Exception:
+                pass