Newer versions of tmux than available in epel6 because I also provide a version of libevent that REPLACES the version in RHEL6 proper but after a certain amount of testing on my own systems I'm relatively confident that it doesn't break anything. The amount of packages that depend on it are pretty small. Also, note that I have filed a RFE BZ in hopes that this is only a temporary solution.
This is a companion discussion topic for the original entry at https://copr.fedorainfracloud.org/coprs/maxamillion/epel6-tmux/