How do I work around a "Could not resolve host: (nil)..." error when installing Homebrew?

How do I work around a "Could not resolve host: (nil)..." error when
installing Homebrew?

I'm trying to install Homebrew on OS X 10.8.4, and get the following:
$ ruby -e "$(curl -fsSL https://raw.github.com/mxcl/homebrew/go)"
==> This script will install:
/usr/local/bin/brew
/usr/local/Library/...
/usr/local/share/man/man1/brew.1
Press ENTER to continue or any other key to abort
==> Downloading and Installing Homebrew...
error: Could not resolve host: (nil); nodename nor servname provided, or
not known while accessing
https://github.com/mxcl/homebrew/info/refs?service=git-upload-pack
fatal: HTTP request failed
Failed during: git fetch origin master:refs/remotes/origin/master -n
What is causing this problem? How do I work around it?
Update (with answers to the questions in sameetandpotatoes's comment):
$ curl -Lsf http://github.com/mxcl/homebrew/tarball/master | tar xz
--strip 1 -C /usr/local
bin/: Can't update time for bin
share/: Can't update time for share
share/man/: Can't update time for share/man
share/man/man1/: Can't update time for share/man/man1
tar: Error exit delayed from previous errors.
$ ruby --version
ruby 1.8.7 (2012-02-08 patchlevel 358) [universal-darwin12.0]
$ gcc --version
i686-apple-darwin11-llvm-gcc-4.2 (GCC) 4.2.1 (Based on Apple Inc. build
5658) (LLVM build 2336.11.00)
I haven't installed Xcode. But I did install "Command Line Tools (OS X
Mountain Lion) for Xcode - April 2013" from
https://developer.apple.com/downloads/index.action.