Etch to Lenny trouble with libxml2

While upgrading a few Debian Etch systems to Lenny, I had a lot of trouble which showed up like this:

symbol lookup error: /usr/lib/libxml2.so.2: undefined symbol: gzopen64

The real cause seems to have been that I had 2 libz libraries installed:

 # /sbin/ldconfig -pNX | grep libz
 libz.so.1 (libc6) => /lib/libz.so.1
 libz.so.1 (libc6) => /usr/lib/libz.so.1

So the solution was quite simple:

 # rm /lib/libz.so.1*

That's all that was needed to get rid of the mountain of dpkg errors, and continue the upgrades following the Debian guide. The next upgrade to Squeeze went smoothly.

For the benefit of Google searchers, here is a full error listing:

 Unpacking replacement shared-mime-info ...
update-mime-database: symbol lookup error: /usr/lib/libxml2.so.2: undefined symbol: gzopen64
dpkg: warning - old post-removal script returned error exit status 127
dpkg - trying script from the new package instead ...
update-mime-database: symbol lookup error: /usr/lib/libxml2.so.2: undefined symbol: gzopen64
dpkg: error processing /var/cache/apt/archives/shared-mime-info_0.30-2_i386.deb (--unpack):
 subprocess new post-removal script returned error exit status 127
update-mime-database: symbol lookup error: /usr/lib/libxml2.so.2: undefined symbol: gzopen64
dpkg: error while cleaning up:
 subprocess post-removal script returned error exit status 127
Preparing to replace libgnomevfs2-common 1:2.14.2-7 (using .../libgnomevfs2-common_1%3a2.22.0-5_all.deb) ...
Unpacking replacement libgnomevfs2-common ...
gconftool-2: symbol lookup error: /usr/lib/libxml2.so.2: undefined symbol: gzopen64
dpkg: warning - old post-removal script returned error exit status 127
dpkg - trying script from the new package instead ...
gconftool-2: symbol lookup error: /usr/lib/libxml2.so.2: undefined symbol: gzopen64
dpkg: error processing /var/cache/apt/archives/libgnomevfs2-common_1%3a2.22.0-5_all.deb (--unpack):
 subprocess new post-removal script returned error exit status 127
gconftool-2: symbol lookup error: /usr/lib/libxml2.so.2: undefined symbol: gzopen64
dpkg: error while cleaning up:
 subprocess post-removal script returned error exit status 127
Preparing to replace libgnome2-common 2.16.0-2 (using .../libgnome2-common_2.20.1.1-1_all.deb) ...
Unpacking replacement libgnome2-common ...
gconftool-2: symbol lookup error: /usr/lib/libxml2.so.2: undefined symbol: gzopen64
dpkg: warning - old post-removal script returned error exit status 127
dpkg - trying script from the new package instead ...
gconftool-2: symbol lookup error: /usr/lib/libxml2.so.2: undefined symbol: gzopen64
dpkg: error processing /var/cache/apt/archives/libgnome2-common_2.20.1.1-1_all.deb (--unpack):
 subprocess new post-removal script returned error exit status 127
gconftool-2: symbol lookup error: /usr/lib/libxml2.so.2: undefined symbol: gzopen64
dpkg: error while cleaning up:
 subprocess post-removal script returned error exit status 127
Errors were encountered while processing:
 /var/cache/apt/archives/shared-mime-info_0.30-2_i386.deb
 /var/cache/apt/archives/libgnomevfs2-common_1%3a2.22.0-5_all.deb
 /var/cache/apt/archives/libgnome2-common_2.20.1.1-1_all.deb
E: Sub-process /usr/bin/dpkg returned an error code (1)
A package failed to install.  Trying to recover:
dpkg: dependency problems prevent configuration of libbonoboui2-0:
 libbonoboui2-0 depends on libglade2-0 (>= 1:2.6.1); however:
  Version of libglade2-0 on system is 1:2.6.0-4.
 libbonoboui2-0 depends on libgtk2.0-0 (>= 2.12.0); however:
  Version of libgtk2.0-0 on system is 2.8.20-7.
dpkg: error processing libbonoboui2-0 (--configure):
 dependency problems - leaving unconfigured
dpkg: dependency problems prevent configuration of libgnomecanvas2-0:
 libgnomecanvas2-0 depends on libglade2-0 (>= 1:2.6.1); however:
  Version of libglade2-0 on system is 1:2.6.0-4.
 libgnomecanvas2-0 depends on libgtk2.0-0 (>= 2.12.0); however:
  Version of libgtk2.0-0 on system is 2.8.20-7.
dpkg: error processing libgnomecanvas2-0 (--configure):
 dependency problems - leaving unconfigured
dpkg: dependency problems prevent configuration of libgail18:
 libgail18 depends on libgtk2.0-0 (>= 2.12.0); however:
  Version of libgtk2.0-0 on system is 2.8.20-7.
dpkg: error processing libgail18 (--configure):
 dependency problems - leaving unconfigured
dpkg: dependency problems prevent configuration of libgail-common:
 libgail-common depends on libgail18 (>= 1.9.1); however:
  Package libgail18 is not configured yet.
 libgail-common depends on libgtk2.0-0 (>= 2.12.0); however:
  Version of libgtk2.0-0 on system is 2.8.20-7.
dpkg: error processing libgail-common (--configure):
 dependency problems - leaving unconfigured
dpkg: dependency problems prevent configuration of libgnomevfs2-extra:
 libgnomevfs2-extra depends on libgnomevfs2-common (>= 1:2.22); however:
  Package libgnomevfs2-common is not installed.
 libgnomevfs2-extra depends on libgnomevfs2-common (<< 1:2.23); however:
  Package libgnomevfs2-common is not installed.
dpkg: error processing libgnomevfs2-extra (--configure):
 dependency problems - leaving unconfigured
dpkg: dependency problems prevent configuration of libgnomevfs2-0:
 libgnomevfs2-0 depends on libgnomevfs2-common (>= 1:2.22); however:
  Package libgnomevfs2-common is not installed.
 libgnomevfs2-0 depends on libgnomevfs2-common (<< 1:2.23); however:
  Package libgnomevfs2-common is not installed.
dpkg: error processing libgnomevfs2-0 (--configure):
 dependency problems - leaving unconfigured
Setting up libgnome-keyring0 (2.22.3-2) ...
dpkg: dependency problems prevent configuration of libgnome2-0:
 libgnome2-0 depends on libgnomevfs2-0 (>= 1:2.17.90); however:
  Package libgnomevfs2-0 is not configured yet.
 libgnome2-0 depends on libgnome2-common (>= 2.20); however:
  Package libgnome2-common is not installed.
 libgnome2-0 depends on libgnome2-common (<< 2.21); however:
  Package libgnome2-common is not installed.
dpkg: error processing libgnome2-0 (--configure):
 dependency problems - leaving unconfigured
dpkg: dependency problems prevent configuration of xserver-xorg-input-mouse:
 xserver-xorg-input-mouse depends on xserver-xorg-core (>= 2:1.4); however:
  Version of xserver-xorg-core on system is 2:1.1.1-21etch5.
dpkg: error processing xserver-xorg-input-mouse (--configure):
 dependency problems - leaving unconfigured
dpkg: dependency problems prevent configuration of xserver-xorg-input-kbd:
 xserver-xorg-input-kbd depends on xserver-xorg-core (>= 2:1.4); however:
  Version of xserver-xorg-core on system is 2:1.1.1-21etch5.
dpkg: error processing xserver-xorg-input-kbd (--configure):
 dependency problems - leaving unconfigured
Errors were encountered while processing:
 libbonoboui2-0
 libgnomecanvas2-0
 libgail18
 libgail-common
 libgnomevfs2-extra
 libgnomevfs2-0
 libgnome2-0
 xserver-xorg-input-mouse
 xserver-xorg-input-kbd