Homebrew/homebrew — pull request #25392 by cbarrick (2013-12-21 22:11:49+00:00)
Title: zsh: `--enable-etcdir` becomes `--enable-etcdir=/etc`. Fixes #25391

I'm not sure that `--disable-etcdir` should even be the default. See #24538. Anyway, this reenables sourcing `/etc/zshenv` etc.