There is no /usr/libexec/uucp/uucico in base; uucico (8) is provided by
the net/uccp package and is installed under /usr/local/. Since we don't
want a shell that default to /usr/local/..., use /sbin/nologin.
The uucp package will automatically change to the correct shell on
pkg_add / pkg_delete.
idea from and ok miod@