add optional BASE-DIRECTORY argument to SAVE-SOME-BUFFERS?

Hi all, I would like to know if there is support for adding another optional argument to save-some-buffers, "base-directory". If non-null, buffers visiting files not located under the base-directory would be skipped. I would like to use this in pcl-cvs so it will stop stupidly asking me if I want to save my mail file when I am running M-x cvs-update in an unrelated directory. If there is interest, I will submit a patch. I am not subscribed so please copy me on any replies. thanks, Greg