only in patch2:
unchanged:
--- a/core/modules/field_ui/src/Tests/ManageFieldsTest.php
+++ b/core/modules/field_ui/src/Tests/ManageFieldsTest.php
@@ -115,6 +115,7 @@ function testCRUDFields() {
     $this->manageFieldsPage();
     $this->createField();
     $this->updateField();
+    $this->updateFieldPrevious();
     $this->addExistingField();
     $this->cardinalitySettings();
     $this->fieldListAdminPage();
@@ -215,6 +216,37 @@ function updateField() {
   }
 
   /**
+   * Tests editing an existing field and submitting via the Previous button.
+   */
+  function updateFieldPrevious() {
+    $field_id = 'node.' . $this->contentType . '.' . $this->fieldName;
+    // Go to the field edit page.
+    $this->drupalGet('admin/structure/types/manage/' . $this->contentType . '/fields/' . $field_id . '/storage');
+    $this->assertEscaped($this->fieldLabel);
+
+    // Populate the field settings with new settings.
+    $string = 'updated dummy test string previous';
+    $edit = array(
+      'settings[test_field_storage_setting]' => $string,
+    );
+    $this->drupalPostForm(NULL, $edit, t('Save field settings'));
+
+    // Go to the field edit page.
+    $this->drupalGet('admin/structure/types/manage/' . $this->contentType . '/fields/' . $field_id . '?destinations=1');
+    $edit = array(
+      'settings[test_field_setting]' => $string,
+    );
+    $this->assertText(t('Default value'), 'Default value heading is shown');
+    $this->drupalPostForm(NULL, $edit, t('Previous'));
+
+    // Assert the field settings are correct.
+    $this->assertFieldSettings($this->contentType, $this->fieldName, $string);
+
+    // Assert redirection back to the edit page.
+    $this->assertUrl('admin/structure/types/manage/' . $this->contentType . '/fields/' . $field_id . '/storage');
+  }
+
+  /**
    * Tests adding an existing field in another content type.
    */
   function addExistingField() {