Use the --old path in the diffs produced by the arbitrary diff handler,just like when using --old with the other diff implementations.This resolves a crash when running$ svn diff --old dev/README --new dev/build.conf --summarize* subversion/libsvn_client/diff.c (do_diff_summarize): Provide the right target to the summarize handler.* subversion/libsvn_client/diff_local.c (arbitrary_diff_walker): Use api to detect administrative dir correctly. (svn_client__arbitrary_nodes_diff): Use path1 as target.* subversion/svn/diff-cmd.c (summarize_baton_t): New baton type. (summarize_xml, summarize_regular): Use baton type. (svn_cl__diff): Update caller.* subversion/tests/cmdline/diff_tests.py (diff_url_against_local_mods): Extend test to show that in this mode we see this as a no change. (diff_arbitrary_files_and_dirs): Update expected result.