Bug#819567: extlinux: please sort kernels by version

[Ian Zimmerman <itz@buug.org>]

Package: extlinux
Version: 2:4.05+dfsg-6+deb7u1
Severity: normal

When extlinux-update is writing out the linux.cfg file, it uses the
following shell code:

  # Find linux versions
  _VERSIONS="$(cd /boot && ls vmlinuz-* | grep -v .dpkg-tmp | sed -e 's|vmlinuz-||g' | sort -nr)"

Unfortunately, this results in (for instance) vmlinuz-3.2 being sorted
before vmlinuz-3.16, with the unexpected result that an unattended
reboot will still boot to the old kernel.

It should really use "sort -Vr" instead.  (I made a local diversion of
this file with this fix and it works perfectly.)

-- System Information:
Debian Release: 7.9
  APT prefers oldstable-updates
  APT policy: (500, 'oldstable-updates'), (500, 'oldstable')
Architecture: amd64 (x86_64)

Kernel: Linux 3.16.0-0.bpo.4-amd64 (SMP w/4 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash

Versions of packages extlinux depends on:
ii  debconf [debconf-2.0]  1.5.49
ii  libc6                  2.13-38+deb7u10

Versions of packages extlinux recommends:
pn  os-prober               <none>
ii  syslinux-common         2:4.05+dfsg-6+deb7u1
pn  syslinux-themes-debian  <none>

extlinux suggests no packages.