Bug#640753: libc6 fails to upgrade with a statically linked /bin/true

[David Hauweele <david@hauweele.net>]

Package: libc6
Version: 2.13-18
Severity: important

When using a statically linked /bin/true, libc6 fails to upgrade
from 2.13-16 to 2.13-18 and makes the system completely unusable.

In the function remove_lib64_symlink() inside preinst, the dynamic
loader is used to test if libc is of the same architecture as
coreutils.

However when coreutils's /bin/true was diverted and replaced with a
statically linked version the test does not work and it falsely
believes it can use the native ELF interpreter for mv. Subsequent
directories moves do not work and this results in a broken system.

This problem can be worked around by removing the divert but it
should rather check the loader on /bin/mv itself.

-- System Information:
Debian Release: wheezy/sid
  APT prefers unstable
  APT policy: (500, 'unstable'), (500, 'testing'), (1, 'experimental')
Architecture: amd64 (x86_64)

Kernel: Linux 3.0.0-1-amd64 (SMP w/4 CPU cores)
Locale: LANG=fr_BE.UTF-8, LC_CTYPE=fr_BE.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash

Versions of packages libc6 depends on:
ii  libc-bin  2.13-18
ii  libgcc1   1:4.6.1-9

libc6 recommends no packages.

Versions of packages libc6 suggests:
ii  debconf [debconf-2.0]  1.5.41
ii  glibc-doc              <none>
ii  locales                2.13-18

-- debconf information:
* glibc/upgrade: true
  glibc/disable-screensaver:
  glibc/restart-failed:
* glibc/restart-services: spamassassin exim4 cron atd