Maybe the PATH entry for svn is set on your user but not on
system/apache user? Anyway, chdir is a good solution.
It is a known problem that the log viewer wasn't designed for multiple
repositories, but the xsl should work. I must confess we haven't
tested much with SVNParentPath. We have different virtual hosts for
different repositories, and in rare cases extra Location blocks on the
same host. Could you send me some xml that shows the problem and I'll
add it to the test/sample pages.
/Staffan