When 'PreservePermissions=yes' is set in the config of CVS, cvs segfaults
on checkin of files containing substition keywords. 
Example:

# cd /some/cvs/working/dir
# echo '$Id$' > crashme
# cvs add crashme
cvs add: scheduling file `crashme' for addition
cvs add: use 'cvs commit' to add this file permanently
# cvs commit -m 'no go'
cvs commit: Examining .
RCS file: /some/cvs/working/dir/crashme,v
done
Checking in crashme;
/opt/cvsroot/some/cvs/working/dir/crashme,v  <--  crashme
initial revision: 1.1
done
Segmentation fault (core dumped)