Add test case for reintegrate-like automatic merge with file replacement [1]

[1] http://svn.haxx.se/dev/archive-2013-01/0449.shtml

* subversion/tests/cmdline/merge_automatic_tests.py
  (merge_replacement): New test.
  (test_list): Add merge_replacement test.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1441400 13f79535-47bb-0310-9956-ffa450edef68