reading the raw iso from a CD-Extra (multisession CD)

[Edmund GRIMLEY EVANS <please_reply_to_the_list@rano.org>]

How can one read the raw ISO file system from the second session of a
CD-Extra / multisession / multi-session CD?

Normally I'd use:

dd if=/dev/cdrom of=data.iso bs=1024

The CD-Extra is mountable, but dd doesn't work:

$ dd if=/dev/cdrom of=data.iso bs=1024
dd: reading `/dev/cdrom': Input/output error
0+0 records in
0+0 records out