brew install --head fails with ENOENT

[jzelinskie]

$ brew install --HEAD zed
==> Cloning https://github.com/authzed/zed.git
Updating /Users/jzelinskie/Library/Caches/Homebrew/zed--git
From ssh://github.com/authzed/zed
   838b4a2..c3f2000  main       -> origin/main
==> Checking out branch main
Already on 'main'
Your branch is behind 'origin/main' by 51 commits, and can be fast-forwarded.
  (use "git pull" to update your local branch)
HEAD is now at c3f2000 Merge pull request #41 from ecordell/release
==> Installing zed from authzed/tap
Error: An exception occurred within a child process:
  Errno::ENOENT: No such file or directory - zed