This CVSROOT/ directory is only here to convince CVS to treat the
neighboring directories as CVS repository modules.  Without it, CVS
operations fail with an error like:

  cvs [checkout aborted]: .../main-cvsrepos/CVSROOT: No such file or directory

Of course, CVS doesn't seem to require that there actually be any
files in CVSROOT/, which kind of makes one wonder why it cares about
the directory at all.

Although this directly is only strictly needed when the --use-cvs
option is used, cvs2svn checks that every project has an associated
CVSROOT directory to avoid complicating its bookkeeping.
