>>279
レスありがとうございます。
その通りにやってみましたが、依然として Downloading and installing から進みません。
ただ、エラーメッセージがいくつか表示されるようになりました。

$ ruby -d install.rb
Exception `LoadError' at /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/rubygems.rb:1082 - cannot load such file -- rubygems/defaults/operating_system
Exception `LoadError' at /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/rubygems.rb:1091 - cannot load such file -- rubygems/defaults/ruby
install.rb:34: warning: `*' interpreted as argument prefix
install.rb:43: warning: `*' interpreted as argument prefix
install.rb:44: warning: `*' interpreted as argument prefix
install.rb:138: warning: `*' interpreted as argument prefix
install.rb:142: warning: `*' interpreted as argument prefix
install.rb:175: warning: `*' interpreted as argument prefix
==> This script will install:
/usr/local/bin/brew
/usr/local/Library/...
/usr/local/share/man/man1/brew.1

Press RETURN to continue or any other key to abort
==> Downloading and installing Homebrew...