brew: Can't install on Sierra

$ ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"
==> This script will install:
/usr/local/bin/brew
/usr/local/share/doc/homebrew
/usr/local/share/man/man1/brew.1
/usr/local/share/zsh/site-functions/_brew
/usr/local/etc/bash_completion.d/brew
/usr/local/Homebrew
==> The following existing directories will be made group writable:
/usr/local/bin

Press RETURN to continue or any other key to abort
==> /usr/bin/sudo /bin/chmod g+rwx /usr/local/bin
==> Downloading and installing Homebrew...
remote: Total 0 (delta 0), reused 0 (delta 0), pack-reused 0
HEAD is now at 17bad9a Merge pull request #1374 from sjackman/bottle-checksums
ln: /usr/local/bin/brew: Permission denied
Failed during: ln -sf /usr/local/Homebrew/bin/brew /usr/local/bin/brew

and my system integrity is disabled