Following https://bugzilla.novell.com/show_bug.cgi?id=626876

i tried to extend the key for:

http://download.opensuse.org/repositories/home:/dtufys/xUbuntu_14.04/

using:

$ osc signkey --extend
<status code="ok" />

After two days the key had still the old date (18-Jul-2014) and was expired.
Following http://lists.opensuse.org/opensuse-buildservice/2013-07/msg00025.html
it turned out that one has to rebuild a package in EVERY repository.

The whole process should be documented, and preferably key extension
available through the web interface.