Random behat fails in timeline block

1. Open your terminal and go to your Moodle root folder.
2. Apply the testing patch in the file attached to this issue.
   1. Download the patch file to your moodle root
   2. Apply the patch

      git am 001-TESTING-COMMIT-FOR-MDL-63667.-Do-Not-Integrate.patch

3. Purge Moodle caches from the command line with

   php admin/cli/purge_caches.php

   or if using MDK,

   mdk purge

4. Login to Moodle and view the dashboard page.
5. Verify you don't see an error message "Failed to pre-fetch the template:"
6. Reload the dashboard page several more times
7. Confirm that you don't see the pre-fetch error message
8. Open the browser dev tools and go to the Javascript console.
9. Verify the console contains 2 cases of text like: 
   *****************************
   A2 returned: A2 Includes B:
   B Includes C:
   C Includes D:
   D Includes E:
   E Includes F:
   F
   End E
   End D
   End C
   End B
   End A2
   *****************************
   (It can say A1 or A2)
10. Verify there are no cases without an "F" in the middle.

 Important: After the test, remember to revert your Moodle instances' codebase to the original branch.

• master: git reset --hard origin/master
• 35: git reset --hard origin/MOODLE_35_STABLE
• 34: git reset --hard origin/MOODLE_34_STABLE