The tmux.spec file is missing a BuildRoot definition and a %clean section. rpmlint warns about this. I've got a small patch to address this that I'm attaching, but I also requested co-maintainer access via the Fedora pkgdb because I don't mind taking care of it myself. If you're ok with that, feel free to grant me commit access and I'll help out.
Created attachment 663621 [details] patch to tmux.spec
http://fedoraproject.org/wiki/Packaging:Guidelines#BuildRoot_tag clean and buildroot are no longer needed as of F10/F13