mongodb: enable --HEAD installs.

--HEAD installs the latest stable developer release (not the nightly.)

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

Formula/mongodb.rb

@@ -4,20 +4,44 @@ require 'hardware'
 class Mongodb < Formula
   homepage 'http://www.mongodb.org/'
 
-  if Hardware.is_64_bit? and not ARGV.include? '--32bit'
-    url 'http://fastdl.mongodb.org/osx/mongodb-osx-x86_64-1.6.5.tgz'
-    md5 'f3438db5a5bd3ac4571616f3d19caf00'
-    version '1.6.5-x86_64'
+  if ARGV.build_head?
+    packages = {
+      :x86_64 => {
+        :url => 'http://fastdl.mongodb.org/osx/mongodb-osx-x86_64-1.8.0-rc2.tgz',
+        :md5 => 'b89e065fbc52f76bfe85e2e7bcc59f15',
+        :version => '1.8.0-rc2-x86_64'
+      },
+      :i386 => {
+        :url => 'http://fastdl.mongodb.org/osx/mongodb-osx-i386-1.8.0-rc2.tgz',
+        :md5 => '0fa436dce2459c1d59beeb49c195d138',
+        :version => '1.8.0-rc2-i386'
+      }
+    }
   else
-    url 'http://fastdl.mongodb.org/osx/mongodb-osx-i386-1.6.5.tgz'
-    md5 '064c9c68752968875e4ccaf8801ef031'
-    version '1.6.5-i386'
+    packages = {
+      :x86_64 => {
+        :url => 'http://fastdl.mongodb.org/osx/mongodb-osx-x86_64-1.6.5.tgz',
+        :md5 => 'f3438db5a5bd3ac4571616f3d19caf00',
+        :version => '1.6.5-x86_64'
+      },
+      :i386 => {
+        :url => 'http://fastdl.mongodb.org/osx/mongodb-osx-i386-1.6.5.tgz',
+        :md5 => '064c9c68752968875e4ccaf8801ef031',
+        :version => '1.6.5-i386'
+      }
+    }
   end
 
+  package = (Hardware.is_64_bit? and not ARGV.include? '--32bit') ? packages[:x86_64] : packages[:i386]
+
+  url     package[:url]
+  md5     package[:md5]
+  version package[:version]
+
   skip_clean :all
 
   def options
-    [['--32bit', 'Install the 32-bit version.']]
+    [['--32bit', 'Override arch detection and install the 32-bit version.']]
   end
 
   def install
@@ -33,20 +57,20 @@ class Mongodb < Formula
     (prefix+'org.mongodb.mongod.plist').write startup_plist
   end
 
-  def caveats; <<-EOS
-If this is your first install, automatically load on login with:
-    mkdir -p ~/Library/LaunchAgents
-    cp #{prefix}/org.mongodb.mongod.plist ~/Library/LaunchAgents/
-    launchctl load -w ~/Library/LaunchAgents/org.mongodb.mongod.plist
+  def caveats; <<-EOS.undent
+    If this is your first install, automatically load on login with:
+        mkdir -p ~/Library/LaunchAgents
+        cp #{prefix}/org.mongodb.mongod.plist ~/Library/LaunchAgents/
+        launchctl load -w ~/Library/LaunchAgents/org.mongodb.mongod.plist
 
-If this is an upgrade and you already have the org.mongodb.mongod.plist loaded:
-    launchctl unload -w ~/Library/LaunchAgents/org.mongodb.mongod.plist
-    cp #{prefix}/org.mongodb.mongod.plist ~/Library/LaunchAgents/
-    launchctl load -w ~/Library/LaunchAgents/org.mongodb.mongod.plist
+    If this is an upgrade and you already have the org.mongodb.mongod.plist loaded:
+        launchctl unload -w ~/Library/LaunchAgents/org.mongodb.mongod.plist
+        cp #{prefix}/org.mongodb.mongod.plist ~/Library/LaunchAgents/
+        launchctl load -w ~/Library/LaunchAgents/org.mongodb.mongod.plist
 
-Or start it manually:
-    mongod run --config #{prefix}/mongod.conf
-EOS
+    Or start it manually:
+        mongod run --config #{prefix}/mongod.conf
+    EOS
   end
 
   def mongodb_conf