Please attach your preseed file (with any passwords removed) and the installer syslog (/var/log/installer/syslog if you completed an installation; /var/log/syslog in the running installer).
The fragment you included in your bug report is clearly wrong. It would need to read as follows:
d-i apt-setup/security_host string server
d-i apt-setup/security_path string /hardy/hardy-archive
However, I don't know whether you were just abbreviating or whether that's really what your preseed file looks like.
Please attach your preseed file (with any passwords removed) and the installer syslog (/var/log/ installer/ syslog if you completed an installation; /var/log/syslog in the running installer).
The fragment you included in your bug report is clearly wrong. It would need to read as follows:
d-i apt-setup/ security_ host string server security_ path string /hardy/ hardy-archive
d-i apt-setup/
However, I don't know whether you were just abbreviating or whether that's really what your preseed file looks like.