Yak shaving to get tmux installed on my Mac

gistfile1.txt

$ sudo brew install tmux
[...]
configure: error: "libevent not found"
$ sudo brew install -v tmux
Error: You must `brew link libevent' before tmux can be installed
$ sudo brew link libevent
Linking /usr/local/Cellar/libevent/2.0.21... Warning: Could not link libevent. Unlinking...

Error: Could not symlink file: /usr/local/Cellar/libevent/2.0.21/include/event.h
Target /usr/local/include/event.h already exists. You may need to delete it.
To force the link and delete this file, do:
  brew link --overwrite formula_name

To list all files that would be deleted:
  brew link --overwrite --dry-run formula_name
$ brew link --overwrite --dry-run formula_name
Error: No such keg: /usr/local/Cellar/formula_name

[That's because I'm an idiot and copy & paste whatever a computer tells me to run.]

$ sudo brew update
[...]

Just because.

$ sudo brew link --overwrite --dry-run libevent
Would remove: [...]
$ sudo brew link --overwrite libevent
Linking /usr/local/Cellar/libevent/2.0.21... 25 symlinks created
$ sudo brew install tmux

[Worked!]