As reported here:
the mailing list discussion somewhat died, so I'm filing an issue so it won't
Calling svn_client_diff_peg4() returns the same diff even with reversed
return the exact same diff (always r7:WC, never WC:r7).
Unfortunately, I can't provide a script to reproduce this, because the
CL client doesn't know WC or WORKING as a valid revision argument.
This happens with the Subversion trunk r25805.
I noticed this when testing the "compare with working copy" feature in
the TSVN log dialog, where a patchfile is created from the selected
revision to the working copy, and that patchfile is then 'applied' to
the working copy to get the files in the selected revision (that's
faster than to fetch all the files individually in full).