Within instant Google forgot basics of its embraced AJAX

I love Google, that is most of the developers says. Their day starts with Googling. Google defined standards of search engine industry. They embraced AJAX technology with Gmail, Google Docs etc.  They define standards of how to use AJAX effectively and efficiently. But, unfortunately today I found a usage of improper usage of AJAX in their webpage and that webpage is nothing but their Home page. Firstly, I didn't believe my eyes, I redo it 4-5 times with different browsers then I believed it. They missed handling back button. They didn't clear the result if back button reaches to their home page.

Here are the steps to reproduce it ( if after this post, they still didn't correct it).

1. Go to Google.com, and type whatever query you have and press enter. In my case, I typed "Blender" as I am learning 3D now a days

2. You reach result page, everything remain normal

3. Press back button of your browser. OOPS!!! I reached google home page with background contains previous result.

After this, I thought might be this is problem with Chromium alone as it is nightly build of Chromium. So, I tried it in Firefox also. Thats test is also turn positive thats why I writing this ;)

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Note: It is big because it is Google's Home page. Otherwise, who cares.
I feel sorry for Google guys as they have to come and fix this and its weekend already. sorry guys.