[jsikorski@snowball SRPMS]$ mock --autocache kxmame-2.0-0.2.20070531svn.fc7.src.rpm
init
clean
prep
This may take a while
unpack cache
Traceback (most recent call last):
  File "/usr/bin/mock", line 1046, in <module>
    main()
  File "/usr/bin/mock", line 1043, in main
    do_rebuild(config_opts, srpms)
  File "/usr/bin/mock", line 910, in do_rebuild
    my.prep()
  File "/usr/bin/mock", line 254, in prep
    self._prep_install()
  File "/usr/bin/mock", line 659, in _prep_install
    os.symlink('../yum.conf', os.path.join(yumdir, 'yum.conf'))
OSError: [Errno 17] File exists
[jsikorski@snowball SRPMS]$