I'd prefer that this was fixed upstream by a warning message that is more descriptive, since rcs it is not essensial to LyX.
I agree that only complining about "ci" is a bit minimalistic. The user would have to know about commands like "apt-file search bin/ci" to immediately determine what to install. In addition, any rcs-related menu items or preferences could be greyed out, with e.g. tooltip info describing why and what to do in order to enable them. Best regards Torquil Sørensen
