Reading package lists... Done
Building dependency tree       
Reading state information... Done
The following packages will be upgraded:
  powerd
1 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
Need to get 0 B/61.1 kB of archives.
After this operation, 0 B of additional disk space will be used.
(Reading database ... 40895 files and directories currently installed.)
Preparing to unpack .../powerd_0.16+15.04.20150430-0ubuntu1_armhf.deb ...
Unpacking powerd (0.16+15.04.20150430-0ubuntu1) over (0.16+15.04.20150219-0ubuntu3) ...
dpkg: error processing archive /var/cache/apt/archives/powerd_0.16+15.04.20150430-0ubuntu1_armhf.deb (--unpack):
 unable to make backup link of `./usr/share/powerd/device_configs/config-default.xml' before installing new version: Invalid cross-device link
Processing triggers for ureadahead (0.100.0-19) ...
Processing triggers for dbus (1.8.12-1ubuntu5) ...
Errors were encountered while processing:
 /var/cache/apt/archives/powerd_0.16+15.04.20150430-0ubuntu1_armhf.deb
E: Sub-process /usr/bin/dpkg returned an error code (1)