Bug#203334: cdebconf-udeb: Impossible to set priority unless cdebconf-priority is installed

[Petter Reinholdtsen <pere@hungry.com>]

Package: cdebconf-udeb
Version: 0.39
Severity: important

When building a d-i boot floppy without the cdebconf-priority package
included on the image, it is impossible to use the kernel option
DEBCONF_PRIORITY to set the debconf priority.  I believe this is
because the template debconf/priority is missing in the cdebconf-udeb
package, and only available from the cdebconf-priority package.

The code in rootskel (/lib/debian-installer.d/S50priority) read the
DEBCONF_PRIORITY environment variable and use it to set the
debconf/priority database value.  This fail unless cdebconf-priority
is installed.

I'm not sure what the proper fix is, but I suspect the easiest
solution is to move the template file to the cdebconf-udeb package.