Just seen this. Didn't try locally, can't see an existing issue open:
Drupal core - 8.x fail: http://qa.drupal.org/8.x-status
Overall Summary
==============================================
FAILED: [[SimpleTest]]: [MySQL] 50,588 pass(es), 11 fail(s), and 0 exception(s).
Individual Environment Summaries
==============================================
- [[SimpleTest]]: [MySQL] --
* Drupal\ckeditor\Tests\CKEditorAdminTest (38 pass(es), 11 fail(s), and 0 exception(s))
- [fail] [Other] "Failed to set field editor[settings][plugins][stylescombo][styles] to h1.title|Title
p.callout|Callout
" in CKEditorAdminTest.php on line 120 of Drupal\ckeditor\Tests\CKEditorAdminTest->testAdmin().
- [fail] [Other] "Found the Save configuration button" in CKEditorAdminTest.php on line 120 of Drupal\ckeditor\Tests\CKEditorAdminTest->testAdmin().
- [fail] [Other] "Found the requested form fields at " in CKEditorAdminTest.php on line 120 of Drupal\ckeditor\Tests\CKEditorAdminTest->testAdmin().
- [fail] [Other] "The Editor config entity has the correct settings." in CKEditorAdminTest.php on line 124 of Drupal\ckeditor\Tests\CKEditorAdminTest->testAdmin().
- [fail] [Other] "Failed to set field editor[settings][toolbar][buttons] to [["Undo","|","Redo"],["JustifyCenter"]]" in CKEditorAdminTest.php on line 136 of Drupal\ckeditor\Tests\CKEditorAdminTest->testAdmin().
- [fail] [Other] "Found the Save configuration button" in CKEditorAdminTest.php on line 136 of Drupal\ckeditor\Tests\CKEditorAdminTest->testAdmin().
- [fail] [Other] "Found the requested form fields at " in CKEditorAdminTest.php on line 136 of Drupal\ckeditor\Tests\CKEditorAdminTest->testAdmin().
- [fail] [Other] "The Editor config entity has the correct settings." in CKEditorAdminTest.php on line 139 of Drupal\ckeditor\Tests\CKEditorAdminTest->testAdmin().
- [fail] [Other] "The Editor config entity has the correct settings." in CKEditorAdminTest.php on line 150 of Drupal\ckeditor\Tests\CKEditorAdminTest->testAdmin().
- [fail] [Other] "The "Ultra llama mode" checkbox exists and is checked." in CKEditorAdminTest.php on line 158 of Drupal\ckeditor\Tests\CKEditorAdminTest->testAdmin().
- [fail] [Other] "The Editor config entity has the correct settings." in CKEditorAdminTest.php on line 162 of Drupal\ckeditor\Tests\CKEditorAdminTest->testAdmin().