Bug#349623: tasksel: Use 'df -P' to support long device name

[Kenshi Muto <kmuto@debian.org>]

Package: tasksel
Version: 2.39
Severity: normal

Hi,

I noticed one of test code of tasksel failed.

Jan 24 15:02:13 in-target: /usr/lib/tasksel/tests/desktop: line 63: [: 17%: integer expression expected

Problematic codes are here:
disk=$(df /usr | tail -1 | awk '{print $4}')
if [ "$disk" ] && [ "$disk" -ge "$(expr $min_disk \* 1024 \* 1024)" ]; then

This is because long device name, such as LVM, makes a result of 
'df' to 2 lines.
df /usr
/dev/mapper/Debian-root
                       2108500   673720  1327672 34% /

$4 becomes '34%' instead of 1327672.
Using 'df -P' (use POSIX style. stop breaking after long device name)
will solve this, I think.

Thanks,
-- 
Kenshi Muto
kmuto@debian.org