Body is stripped when title is empty

Originally reported by tomm (http://drupal.org/user/223318).

I am using the fckeditor-6.x-1.1 plugin. I've found a bug. On node
submission, if you have a DrupalBreak in the node body and try saving the
node but haven't filled in some mandatory fields (title, for example), then
the part of the body above the DrupalBreak (the summary) will be lost.