For debugging an issue (https://github.com/owncloud/client/issues/2485), I needed to build the owncloud client from git master.
I looked at http://doc.owncloud.org/desktop/1.7/building.html, but
apt-get build-dep owncloud-client did not work for me, could not find the source package.
So here are the necessary commands for Ubuntu 12.04:
git clone https://github.com/owncloud/client.git owncloudclient cd owncloudclient apt-get install cmake libneon27-dev qt-sdk qtkeychain-dev libsqlite3-dev cmake -DCMAKE_BUILD_TYPE="Debug" make cd bin ./owncloud --logfile -