RegEx to remove double slashes from the Url's

I would like to replace double slashes with single slashes from the below input string except the slashes that followed by ":"  should be ignored

 
String Input =  "http://edition.cnn.com//2009//POLITICS//06//08//scotus?iref=hpmostpop"
Expected Output =  "http://edition.cnn.com/2009/POLITICS/06/08/scotus?iref=hpmostpop"
Note: Please read the above note regd ":"

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