diff --git a/core/tests/Drupal/KernelTests/Core/Entity/ContentEntityConcurrentRevisionSaveTest.php b/core/tests/Drupal/KernelTests/Core/Entity/ContentEntityConcurrentRevisionSaveTest.php
new file mode 100644
index 0000000..cbc3cc5
--- /dev/null
+++ b/core/tests/Drupal/KernelTests/Core/Entity/ContentEntityConcurrentRevisionSaveTest.php
@@ -0,0 +1,120 @@
+<?php
+
+namespace Drupal\KernelTests\Core\Entity;
+
+use Drupal\Core\Entity\ContentEntityInterface;
+use Drupal\entity_test\Entity\EntityTestMulRevChanged;
+
+/**
+ * Tests concurrent entity saves and revisions.
+ *
+ * @group Entity
+ */
+class ContentEntityConcurrentRevisionSaveTest extends EntityKernelTestBase {
+
+  const SAVE_NO_REVISION = 0x0;
+  const SAVE_NEW_REVISION = 0x1;
+  const SAVE_PENDING_REVISION = 0x3;
+
+  /**
+   * Modules to enable.
+   *
+   * @var array
+   */
+  public static $modules = ['user', 'system', 'field', 'text', 'filter', 'entity_test'];
+
+  /**
+   * The EntityTestMulRevChanged entity type storage.
+   *
+   * @var \Drupal\Core\Entity\EntityStorageInterface
+   */
+  protected $storage;
+
+  /**
+   * Counter used to generate meaningful entity labels.
+   *
+   * @var int
+   */
+  protected $saveCounter;
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp() {
+    parent::setUp();
+    $this->installEntitySchema('entity_test_mulrev_changed');
+    $this->storage = $this->entityManager->getStorage('entity_test_mulrev_changed');
+    $this->saveCounter = 1;
+  }
+
+  /**
+   * Data provider for testConcurrentSave().
+   */
+  public function dataTestConcurrentSave() {
+    return [
+      'pending revision - pending revision' => [[static::SAVE_PENDING_REVISION, static::SAVE_PENDING_REVISION]],
+      'no revision - pending revision' => [[static::SAVE_NO_REVISION, static::SAVE_PENDING_REVISION]],
+      'new revision - pending revision' => [[static::SAVE_NEW_REVISION, static::SAVE_PENDING_REVISION]],
+      'pending revision - no revision' => [[static::SAVE_PENDING_REVISION, static::SAVE_NO_REVISION]],
+      'no revision - no revision' => [[static::SAVE_NO_REVISION, static::SAVE_NO_REVISION]],
+      'new revision - no revision' => [[static::SAVE_NEW_REVISION, static::SAVE_NO_REVISION]],
+      'pending revision - new revision' => [[static::SAVE_PENDING_REVISION, static::SAVE_NEW_REVISION]],
+      'no revision - new revision' => [[static::SAVE_NO_REVISION, static::SAVE_NEW_REVISION]],
+      'new revision - new revision' => [[static::SAVE_NEW_REVISION, static::SAVE_NEW_REVISION]],
+    ];
+  }
+
+  /**
+   * Tests concurrent entity saves with various save types.
+   *
+   * @param int[] $type
+   *   An array of save types as defined by the related ::SAVE_* constants. One
+   *   for each of the two concurrent saves.
+   *
+   * @covers \Drupal\Core\Entity\Plugin\Validation\Constraint\EntityChangedConstraintValidator::validate
+   *
+   * @dataProvider dataTestConcurrentSave
+   */
+  public function testConcurrentSave(array $type) {
+    $user = $this->createUser();
+
+    // Create a test entity.
+    $entity = EntityTestMulRevChanged::create([
+      'not_translatable' => $this->randomString(),
+      'user_id' => $user->id(),
+      'language' => 'en',
+    ]);
+    $this->doEntitySave($entity, static::SAVE_NO_REVISION, FALSE);
+
+    // Perform two "concurrent" saves and verify the second one triggers a
+    // validation error.
+    $entity_other_instance = clone $entity;
+    $this->doEntitySave($entity, $type[0], FALSE);
+    $this->doEntitySave($entity_other_instance, $type[1], TRUE);
+  }
+
+  /**
+   * Performs an entity save of the specified "type".
+   *
+   * @param \Drupal\Core\Entity\ContentEntityInterface $entity
+   *   The entity to be saved.
+   * @param int $type
+   *   The save type, as defined by the ::SAVE_* constants.
+   * @param bool $error_expected
+   *   Flag indicating whether a validation error is expected.
+   */
+  protected function doEntitySave(ContentEntityInterface $entity, $type, $error_expected) {
+    // Set a meaningful entity label, useful for debugging.
+    $entity->set('name', 'Title ' . ($this->saveCounter++));
+    if ($type & static::SAVE_NEW_REVISION) {
+      $entity->setNewRevision();
+    }
+    if ($type == static::SAVE_PENDING_REVISION) {
+      $entity->isDefaultRevision(FALSE);
+    }
+    $violations = $entity->validate();
+    $this->assertEquals($error_expected, (bool) $violations->count());
+    $entity->save();
+  }
+
+}
diff --git a/core/tests/Drupal/KernelTests/Core/Entity/EntityLoadedRevisionTest.php b/core/tests/Drupal/KernelTests/Core/Entity/EntityLoadedRevisionTest.php
index a3b99fe..5659280 100644
--- a/core/tests/Drupal/KernelTests/Core/Entity/EntityLoadedRevisionTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Entity/EntityLoadedRevisionTest.php
@@ -167,4 +167,35 @@ public function testSaveInHookEntityInsert() {
 
   }
 
+  /**
+   * Tests manual revert of the revision id value.
+   *
+   * @covers \Drupal\Core\Entity\ContentEntityBase::getRevisionId
+   * @covers \Drupal\Core\Entity\ContentEntityBase::getLoadedRevisionId
+   * @covers \Drupal\Core\Entity\ContentEntityBase::setNewRevision
+   */
+  public function testNewRevisionRevert() {
+    $entity = EntityTestMulRev::create(['name' => 'EntityLoadedRevisionTest']);
+    $entity->save();
+
+    // Check that revision id field is reset while the loaded revision id is
+    // preserved when flagging a new revision.
+    $revision_id = $entity->getRevisionId();
+    $entity->setNewRevision();
+    $this->assertNull($entity->getRevisionId());
+    $this->assertEquals($revision_id, $entity->getLoadedRevisionId());
+
+    // Check that manually reverting the new revision state by assigning a value
+    // to the revision id field works as expected.
+    $key = $entity->getEntityType()->getKey('revision');
+    $entity->set($key, $revision_id);
+    $this->assertEquals($revision_id, $entity->getRevisionId());
+    $this->assertEquals($revision_id, $entity->getLoadedRevisionId());
+
+    // Check that flagging a new revision again works correctly.
+    $entity->setNewRevision();
+    $this->assertNull($entity->getRevisionId());
+    $this->assertEquals($revision_id, $entity->getLoadedRevisionId());
+  }
+
 }