serf fails to build on 10.8.4

gistfile1.txt

HOMEBREW_MAKE_JOBS=1 VERBOSE=1 brew install svn 2>&1
==> Installing subversion dependency: serf
==> Downloading http://serf.googlecode.com/files/serf-1.2.1.tar.bz2
Already downloaded: /Library/Caches/Homebrew/serf-1.2.1.tar.bz2
tar xf /Library/Caches/Homebrew/serf-1.2.1.tar.bz2
Error: undefined local variable or method `superbin' for serf:Serf
Please report this bug:
    https://github.com/mxcl/homebrew/wiki/troubleshooting
/usr/local/Library/Formula/serf.rb:14:in `apr_bin'
/usr/local/Library/Formula/serf.rb:20:in `install'
/usr/local/Library/Homebrew/build.rb:172:in `install'
/usr/local/Library/Homebrew/formula.rb:239:in `brew'
/usr/local/Library/Homebrew/formula.rb:600:in `stage'
/usr/local/Library/Homebrew/extend/fileutils.rb:21:in `mktemp'
/usr/local/Library/Homebrew/formula.rb:596:in `stage'
/usr/local/Library/Homebrew/formula.rb:234:in `brew'
/usr/local/Library/Homebrew/build.rb:151:in `install'
/usr/local/Library/Homebrew/build.rb:44:in `main'
/usr/local/Library/Homebrew/build.rb:12
/usr/local/Library/Formula/serf.rb:17

Nothing in ~/Library/Logs/Homebrew/serf:
~/Library/Logs/Homebrew/serf 542 $ ls -al
total 0
drwxr-xr-x  2 steve  staff   68 Aug 19 12:26 .
drwxr-xr-x  9 steve  staff  306 Aug 19 12:25 ..

~/Library/Logs/Homebrew/serf $ brew doctor
Your system is ready to brew.