Documentation of files_private

It appears that "drush quickstart-create" or "drush qc" sets the private file directory to "sites/default/files_private." The message you get is "file_private_path was set to sites/default/files_private."

This can be confusing if you're developing an install profile that explicitly sets the private file directory :)

If this is documented somewhere, I was not able to find it, and searching the issue queue did not explicitly spell it out.