amd64-libs fails to upgrade because of dpkg bug

[Daniel Jacobowitz <dan@debian.org>]

I have been looking at #362960 and #419109.  They're both failures of
this form during a sarge -> etch upgrade:

dpkg-divert: rename involves overwriting `/usr/include/asm/a.out.h' with
  different file `/usr/include/asm-i386/a.out.h', not allowed

I eventually worked out that this is caused by dpkg bug #310390, which
affects the version in sarge but not etch.  When it upgrades
amd64-libs, it fails to remove that package's copy of a.out.h.  Then
when the postinst tries to remove the diversion things fall down.

I tried manually upgrading dpkg before apt-get upgrade; then the bug
doesn't show up.  Installing dpkg updates libc6 to etch but not
amd64-libs.

I don't know how to prevent others from hitting this.  Would
predepending on a sufficiently new dpkg work?

-- 
Daniel Jacobowitz
CodeSourcery