If you install the plugin, and immediately check it into SVN,
before the rake installer task runs, the installer file copier
copies the .SVN directories from vendor/plugins/tiny_mce to
public/javascripts/tiny_mce, which royally screws up
subversion.
For the plugin user, the correct sequence is to install the
plugin, run the rake task, then check both vendor/plugins/tiny_mce
and public/javascripts/tiny_mce into subversion. But if you do any
of this in the wrong order, all hell breaks loose.
The correct way to fix this is to exclude (recursively) any .SVN
directories you find during the file copy. Using FileUtils.cp_r is
too general.