I had the same problem, and I did, after which I fixed it.
1.
ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)" < /dev/null 2> /dev/null
2.
MBP:~$ brew install terraform
==> Downloading https://homebrew.bintray.com/bottles/terraform-0.7.5.el_capitan.bottle.tar.gz
100.0%
==> Pouring terraform-0.7.5.el_capitan.bottle.tar.gz
==> Caveats
zsh completion has been installed to:
/usr/local/share/zsh/site-functions
==> Summary
🍺 /usr/local/Cellar/terraform/0.7.5: 4 files, 123.3M
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