added some git rake tasks

Rakefile

@@ -1,3 +1,5 @@
+require 'readline'
+require 'find'
 
 MYDIR  = File.dirname(__FILE__)
 DOCDIR = "#{MYDIR}/doc"
@@ -48,3 +50,120 @@ namespace "doc" do
 end
 
 task :default => :'test:emacs'
+
+# some git tasks taken from the rubinius
+def git_branch
+  `git branch | grep "*"`.strip[2..-1]
+end
+
+def compare_git_ver
+  m = /git version (\d+).(\d+).(\d+)/.match(`git version`.strip)
+  return true  if m[1].to_i > 1
+  return false if m[1].to_i < 1
+  return true  if m[2].to_i > 5
+  return false if m[2].to_i < 5
+  return true  if m[3].to_i >= 3
+  return false
+end
+
+def check_git_ver
+  raise "Invalid git version, use at least 1.5.3" unless compare_git_ver
+end
+
+namespace :git do
+
+  desc "Show the current status of the checkout"
+  task :status do
+    system "git status"
+  end
+
+  desc "Create a new topic branch"
+  task :topic do
+    total = `git branch`.scan("quick").size
+    if total == 0
+      default = "quick"
+    else
+      default = "quick#{total + 1}"
+    end
+    name = Readline.readline "Topic name (default #{default}): "
+    if name.strip.empty?
+      name = default
+    end
+    sh "git checkout -b #{name}"
+  end
+
+  desc "Push all changes to the repository"
+  task :push => :update do
+    branch = git_branch()
+    if branch != "master"
+      `git diff-files --quiet`
+      if $?.exitstatus == 1
+        puts "You have outstanding changes. Please commit them first."
+        exit 1
+      end
+
+      puts "* Merging topic '#{branch}' back into master..."
+      `git checkout master`
+      sh "git merge #{branch}"
+      switch = true
+    else
+      switch = false
+    end
+
+    puts "* Pushing changes..."
+    sh "git push"
+
+    if switch
+      puts "* Switching back to #{branch}..."
+      `git checkout #{branch}`
+    end
+  end
+
+  desc "Pull new commits from the repository"
+  task :update do
+    check_git_ver
+    `git diff-files --quiet`
+    if $?.exitstatus == 1
+      stash = true
+      clear = `git stash list`.scan("\n").size == 0
+      puts "* Saving changes..."
+      `git stash save`
+    else
+      stash = false
+    end
+
+    branch = git_branch()
+    if branch != "master"
+      switch = true
+      `git checkout master`
+      puts "* Switching back to master..."
+    else
+      switch = false
+    end
+
+    puts "* Pulling in new commits..."
+    sh "git fetch"
+    sh "git rebase origin"
+
+    if switch
+      puts "* Porting changes into #{branch}..."
+      `git checkout #{branch}`
+      sh "git rebase master"
+    end
+
+    if stash
+      puts "* Applying changes..."
+      sh "git stash apply"
+      `git stash clear` if clear
+    end
+  end
+
+  task :pull => :update
+
+  desc "remove all .git folders from the directory"
+  task :clean do
+    Find.find("./"){|f| FileUtils.rm_rf(f) if f =~ /\.git.*/}
+  end
+
+end
+# end some git tasks taken from the rubinius