debconf-set code 20?

[Ed Kohlwey <ekohlwey@gmail.com>]

Hi,

I'm trying to use the partman/early_command setting to set partman-auto-lvm/extra_devices. Debconf-set fails silently with exit code 20.

When trying to run the command from another vt I get the same result; this result is also the same as running debconf-set for a value I know shouldn't be set (like debconf-set foo). Setting, for instance, partman-auto/disk returns code 0.

I'd guess I'm missing some package that "provides" this setting that I need to install before calling partman-set?