Drat!  It returned back to the dreaded 

dpkg: ../../src/archives.c:985: tarobject: Assertion `r == stab.st_size' failed.
 
deadlock.


Here is the tail ending of hours of    apt-get install -f
* Installing 1 assembly from libflickrnet2.2-cil into Mono
Setting up f-spot (0.8.2-4) ...
Setting up libmono-system2.0-cil (2.10.5-1) ...
Setting up libmono-data-tds2.0-cil (2.10.5-1) ...
Setting up libmono-management2.0-cil (2.10.5-1) ...
Setting up libmono-messaging2.0-cil (2.10.5-1) ...
Setting up libmono-sharpzip2.84-cil (2.10.5-1) ...
Setting up libmono-simd2.0-cil (2.10.5-1) ...
Setting up libmono-system-data2.0-cil (2.10.5-1) ...
Setting up libmono-sqlite2.0-cil (2.10.5-1) ...
Setting up libmono-system-messaging2.0-cil (2.10.5-1) ...
Setting up libmono-wcf3.0-cil (2.10.5-1) ...
Setting up libmono-system-data-linq2.0-cil (2.10.5-1) ...
Setting up libmono-system-web2.0-cil (2.10.5-1) ...
Setting up libmono2.0-cil (2.10.5-1) ...
Setting up libmono-system-runtime2.0-cil (2.10.5-1) ...
Setting up mono-gmcs (2.10.5-1) ...
Processing triggers for python-central ...
Setting up python-wxgtk2.6 (2.6.3.2.2-5ubuntu3) ...
update-alternatives: using /usr/lib/wx/python/wx2.6.pth to provide /usr/lib/python2.6/dist-packages/wx.pth (wx2.6.pth) in auto mode.
update-alternatives: using /usr/lib/wx/python/wx2.6.pth to provide /usr/lib/python2.7/dist-packages/wx.pth (wx2.7.pth) in auto mode.
Setting up python-wxgtk2.8 (2.8.11.0-0ubuntu10) ...
update-alternatives: using /usr/lib/wx/python/wx2.8.pth to provide /usr/lib/python2.6/dist-packages/wx.pth (wx2.6.pth) in auto mode.
update-alternatives: using /usr/lib/wx/python/wx2.8.pth to provide /usr/lib/python2.7/dist-packages/wx.pth (wx2.7.pth) in auto mode.
Processing triggers for libc-bin ...
ldconfig deferred processing now taking place
Processing triggers for initramfs-tools ...
update-initramfs: Generating /boot/initrd.img-3.0.0-22-generic
Warning: No support for locale: en_US.utf8
Warning: Not updating LILO; /etc/lilo.conf not found
Warning: Not updating LILO; /etc/lilo.conf not found!
Processing triggers for python-support ...
Processing triggers for dictionaries-common ...
Processing triggers for menu ...
Processing triggers for python-central ...
Cannot find md5sums path for python-twisted-core
N: Ignoring file 'apt-build' in directory '/etc/apt/sources.list.d/' as it has no filename extension
N: Ignoring file 'apt-build' in directory '/etc/apt/sources.list.d/' as it has no filename extension
E: Problem executing scripts DPkg::Post-Invoke 'if [ -x /usr/bin/debsums ]; then /usr/bin/debsums --generate=nocheck -sp /var/cache/apt/archives; fi'
E: Sub-process returned an error code
 
In synaptic I marked python-twisted-core for reinstall, which caused it to re-download to 
 /var/cache/apt/archives/python-twisted-core_11.0.0-2_all.deb


Though that attempt to reinstall the package ended in failure:

E: dpkg was interrupted, you must manually run 'dpkg --configure -a' to correct the problem.
E: _cache->open() failed, please report.


This time, instead of running 'dpkg --configure -a' again, esp. since I noticed the /var/lib/dpkg/updates already empty, I ran:

 dpkg -i  --force-all /var/cache/apt/archives/python-twisted-core_11.0.0-2_all.deb

which output:

(Reading database ... 
dpkg: warning: files list file for package `python-twisted-core' missing, assuming package has no files currently installed.
(Reading database ... 295426 files and directories currently installed.)
Preparing to replace python-twisted-core 11.0.0-2 (using .../python-twisted-core_11.0.0-2_all.deb) ...
Unpacking replacement python-twisted-core ...
dpkg: ../../src/archives.c:985: tarobject: Assertion `r == stab.st_size' failed.


Soooo that pretty much circles back to square one.

Maybe someone could post their "Package: python-twisted-core" stanza from /var/lib/dpkg/status for me? The one in comment#4 above was from one other presumably healthy Ubuntu server, but there could be version mismatches etc.