Several people have written patches to extend PUSH_REMOTE to be able to push a branch other than master. For example,

It seems that these are not fully flexible either. Maybe someone wants to push 2 branches, or push different branches to different remotes.

I think that adding PUSH_REMOTE was a mistake. It would be better to remove it, and add to the readme an example of writing your own /etc/etckeeper/commit.d/99push script that does exactly the kind of pushing you want. The only reason I've not done so is it would break compatability for anyone using this feature. --?Joey