If you hit this issue, the work around is explained here:
https://fedoraproject.org/wiki/Common_F20_bugs#tmux-upgrade-issues Only two
users reported this issue, that is reproducible in a very specific case, so I
believe we can live with that, at least on F20. I'm 0 to unpush this update, so
lets see if no more users complain about it, so we decide if it should be to
stable or should be unpushed.