Add a test for issue #4310 "each editor drive gets its own notification
during 'svn merge'".

* subversion/tests/cmdline/merge_tests.py

  (multiple_editor_drive_merge_notifications): New test.

  (test_list): Add multiple_editor_drive_merge_notifications.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1441553 13f79535-47bb-0310-9956-ffa450edef68