On the latest master branch,

I think adding shebang line in Rakefile is not suitable. Because shebang is used on the executable bit file. But it is not executed like ./Rakefile.

It can be just like this.

$ git diff Rakefile
diff --git a/Rakefile b/Rakefile
index 996ea5ad2..31f765565 100644
--- a/Rakefile
+++ b/Rakefile
@@ -1,5 +1,3 @@
-#!/usr/bin/env ruby
-
 require 'rubygems'
 
 begin

See https://en.wikipedia.org/wiki/Shebang_(Unix) for detail.