libverto allows to use arbitrary backends, unfortunately the libverto package does not have any requirement to install at least on so gssproxy will simply miseriously fail to start if none is avaialble.
For now I suggest we add Requires: libverto-tevent
Fixed in gssproxy-0.2.2-5.fc19
Metadata Update from @simo: - Issue assigned to gd - Issue set to the milestone: 2013 June