Got a brew install error

[reggi]

thomas@workstation:example$ brew install stdbuf
Error: stdbuf is a head-only formula
Install with `brew install --HEAD stdbuf
thomas@workstation:example$ brew install --HEAD stdbuf
==> Cloning https://github.com/tcreech/stdbuf-osx.git
Cloning into '/Library/Caches/Homebrew/stdbuf--git'...
remote: Counting objects: 6, done.
remote: Compressing objects: 100% (6/6), done.
remote: Total 6 (delta 0), reused 5 (delta 0)
Unpacking objects: 100% (6/6), done.
Checking connectivity... done
==> make
/usr/local/Library/ENV/4.3/make: /usr/local/Library/ENV/4.3/xcrun: /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/bin/ruby: bad interpreter: No such file or directory
/usr/local/Library/ENV/4.3/make: line 3: /usr/local/Library/ENV/4.3/xcrun: Undefined error: 0
Error: Homebrew doesn't know what compiler versions ship with your version
of Xcode (6.1.1). Please `brew update` and if that doesn't help, file
an issue with the output of `brew --config`:
  https://github.com/Homebrew/homebrew/issues

Note that we only track stable, released versions of Xcode.

Thanks!

READ THIS: https://github.com/Homebrew/homebrew/wiki/troubleshooting
If reporting this issue please do so at (not Homebrew/homebrew):
  https://github.com/paulp/homebrew-extras/issues