Fix a random jobs error.

Once in a while, build will fail with:

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
ERROR: Cannot copy '../../../../../subversion/bindings/swig/perl/native/Core.pm' to 'blib/lib/SVN/Core.pm': Permission denied
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
at -e line 1.