Use Travis https build status image in order to prevent GitHub from

caching the http version.

The syntax for including an https image url in RDoc taken from
http://about.travis-ci.org/docs/user/status-images. Having this in a
line of its own now to make regex replacement for the API simpler!

README.rdoc

@@ -61,13 +61,14 @@ can read more about Action Pack in its {README}[link:/rails/rails/blob/master/ac
 * The {Ruby on Rails Guides}[http://guides.rubyonrails.org].
 * The {API Documentation}[http://api.rubyonrails.org].
 
-
-== Contributing http://travis-ci.org/rails/rails.png
+== Contributing
 
 We encourage you to contribute to Ruby on Rails! Please check out the {Contributing to Rails
 guide}[http://edgeguides.rubyonrails.org/contributing_to_ruby_on_rails.html] for guidelines about how
 to proceed. {Join us}[http://contributors.rubyonrails.org]!
 
+== Travis Build Status {<img src="https://secure.travis-ci.org/rails/rails.png"/>}[https://secure.travis-ci.org/rails/rails.png]
+
 == License
 
 Ruby on Rails is released under the MIT license.

Rakefile

@@ -78,7 +78,8 @@ RDoc::Task.new do |rdoc|
     rdoc_main.gsub!(%r{link:/rails/rails/blob/master/(\w+)/README\.rdoc}, "link:files/\\1/README_rdoc.html")
 
     # Remove Travis build status image from API pages. Only GitHub README page gets this image
-    rdoc_main.gsub!("http://travis-ci.org/rails/rails.png", "")
+    # https build image is used to avoid GitHub caching: http://about.travis-ci.org/docs/user/status-images
+    rdoc_main.gsub!(%r{^== Travis.*}, '')
 
     File.open(RDOC_MAIN, 'w') do |f|
       f.write(rdoc_main)