On the invoke-diff-cmd branch: Ensure that delimiters that have a
  special start characer retain this after expansion.  Add new test.

* subversion/libsvn_subr/io.c

  (__create_custom_diff_cmd): Ensure that ineligible delimiters that
    have a special start characer are not modified.  Ensure that labels
    are passed correctly.

  (svn_io_run_diff2):  Add test location information.

* subversion/tests/cmdline/diff_tests.py

  (diff_invoke_external_diffcmd): Add new tests for the above behavior.

* subversion/svn/svn.c

  (svn_cl__options): Update help text pertaining to invoke-diff-cmd.




git-svn-id: https://svn.apache.org/repos/asf/subversion/branches/invoke-diff-cmd-feature@1529609 13f79535-47bb-0310-9956-ffa450edef68