Comment 8 for bug 349837

aptitude safe-upgrade
Reading package lists... Done
Building dependency tree
Reading state information... Done
Reading extended state information
Initializing package states... Done
Resolving dependencies...
The following NEW packages will be installed:
  python-twisted-calendarserver{a}
The following partially installed packages will be configured:
  calendarserver
0 packages upgraded, 1 newly installed, 0 to remove and 0 not upgraded.
Need to get 0B/242kB of archives. After unpacking 1556kB will be used.
Do you want to continue? [Y/n/?] y
Writing extended state information... Done
(Reading database ... 43095 files and directories currently installed.)
Unpacking python-twisted-calendarserver (from .../python-twisted-calendarserver_0.2.0.svn19773-5ubuntu1_i386.deb) ...
dpkg: error processing /var/cache/apt/archives/python-twisted-calendarserver_0.2.0.svn19773-5ubuntu1_i386.deb (--unpack):
 trying to overwrite `/usr/share/pyshared/twisted/plugins/__init__.py', which is also in package python-twisted-core
dpkg-deb: subprocess paste killed by signal (Broken pipe)
Errors were encountered while processing:
 /var/cache/apt/archives/python-twisted-calendarserver_0.2.0.svn19773-5ubuntu1_i386.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 calendarserver:
 calendarserver depends on python-twisted-calendarserver (>= 0.2.0.svn19773-3); however:
  Package python-twisted-calendarserver is not installed.
dpkg: error processing calendarserver (--configure):
 dependency problems - leaving unconfigured
Errors were encountered while processing:
 calendarserver
Reading package lists... Done
Building dependency tree
Reading state information... Done
Reading extended state information
Initializing package states... Done
Writing extended state information... Done

Same issue during installation of calendarserver with

  apt-get install calendarserver