new formula: git-flow

Git extensions to provide high-level repository operations for Vincent
Driessen's branching model [1].

[1] http://nvie.com/archives/323

Signed-off-by: Adam Vandenberg <flangy@gmail.com>

* Use --HEAD to install development branch.
* Don't depend on brew-installed git; user may already have a git.

Formula/git-flow.rb

@@ -0,0 +1,22 @@
+require 'formula'
+
+class GitFlow <Formula
+  if ARGV.include? "--HEAD"
+    head 'git://github.com/nvie/gitflow.git', :branch => 'develop'
+  else
+    head 'git://github.com/nvie/gitflow.git', :tag => '0.2.1'
+    version '0.2.1'
+  end
+
+  homepage 'http://github.com/nvie/gitflow'
+
+  # You need git to install, since we install from a git repo
+  # You also need git to run the scripts.
+  # But we're not going to mark it as a dependency just yet:
+  #   The user may have a non-brew git installed already.
+  # depends_on 'git'
+
+  def install
+    system "make",  "prefix=#{prefix}", "install"
+  end
+end