the KDE SC 4.12 in kdenext don't play nicely with kdepim-next repo:
LANG=C apt-get -f install
Reading package lists... Done
Building dependency tree
Reading state information... Done
Correcting dependencies... Done
The following packages were automatically installed and are no longer required:
libgroupsock0 liblivemedia7 libserf1 libusageenvironment0 libxcb-sync0 linux-doc-3.10 linux-headers-3.10-3-common linux-headers-3.11-2-common linux-kbuild-3.10 wine64-bin
Use 'apt-get autoremove' to remove them.
The following extra packages will be installed:
kdepimlibs5-dev libakonadi-xml4
The following NEW packages will be installed:
libakonadi-xml4
The following packages will be upgraded:
kdepimlibs5-dev
1 upgraded, 1 newly installed, 0 to remove and 3 not upgraded.
476 not fully installed or removed.
Need to get 0 B/506 kB of archives.
After this operation, 189 kB of additional disk space will be used.
Do you want to continue? [Y/n]
(Reading database ... 482539 files and directories currently installed.)
Preparing to unpack .../kdepimlibs5-dev_4%3a4.12.0-90r2_amd64.deb ...
Unpacking kdepimlibs5-dev (4:4.12.0-90r2) over (4:4.11.4-90r0) ...
dpkg: error processing archive /var/cache/apt/archives/kdepimlibs5-dev_4%3a4.12.0-90r2_amd64.deb (--unpack):
trying to overwrite '/usr/share/kde4/apps/akonadi/akonadi-xml.xsd', which is also in package kdepim-runtime 4:4.11.5+really4.11.2-91r0
dpkg-deb: error: subprocess paste was killed by signal (Broken pipe)
Preparing to unpack .../libakonadi-xml4_4%3a4.12.0-90r2_amd64.deb ...
Unpacking libakonadi-xml4 (4:4.12.0-90r2) ...
dpkg: error processing archive /var/cache/apt/archives/libakonadi-xml4_4%3a4.12.0-90r2_amd64.deb (--unpack):
trying to overwrite '/usr/lib/libakonadi-xml.so.4', which is also in package kdepim-runtime 4:4.11.5+really4.11.2-91r0
Errors were encountered while processing:
/var/cache/apt/archives/kdepimlibs5-dev_4%3a4.12.0-90r2_amd64.deb
/var/cache/apt/archives/libakonadi-xml4_4%3a4.12.0-90r2_amd64.deb
E: Sub-process /usr/bin/dpkg returned an error code (1)