pivotal/tmux-config — pull request #1 by Peeja (2012-09-03 15:30:04+00:00)
Title: Actually, Vims everywhere get autosaved

Unless this changed since I worked on it. But it looks like
VIM_PANES is still set as a global (-g) server variable.

https://github.com/pivotal/tmux-config/blob/master/plugin/autowrite.vim#L17

Typically, there's only one tmux server running on a machine.