Comment 2 for bug 1898129

Testing in Groovy Desktop ISO (daily build 2020-09-30)

Example: usage to specify luks header version,
as LUKS1; the default is LUKS2 on Focal/later.

$ sudo dpkg -i --force-depends --force-overwrite partman-crypto_101ubuntu4+luksopts1_amd64.udeb

Default (no option specified / no changes):
---

$ sudo cryptsetup luksDump /dev/vda4
LUKS header information
Version: 2
...

Option:
---

Preseed file:

"""
ubiquity partman-crypto/luksformat_options string \
  --type luks1
"""

$ sudo debconf-get partman-crypto/luksformat_options
--type luks1

$ grep luksFormat /var/log/partman
/usr/bin/autopartition-crypto: Additional options for luksFormat: '--type luks1'

$ sudo cryptsetup luksDump /dev/vda4
LUKS header information for /dev/vda4

Version: 1
...