Source : Free On-Line Dictionary of Computing

I didn't change anything!
     
        An aggrieved cry often heard as bugs manifest during a
        regression test.  The {canonical} reply to this assertion is
        "Then it works just the same as it did before, doesn't it?"
        See also {one-line fix}.  This is also heard from applications
        programmers trying to blame an obvious applications problem on
        an unrelated systems software change, for example a
        divide-by-0 fault after terminals were added to a network.
        Usually, their statement is found to be false.  Upon close
        questioning, they will admit some major restructuring of the
        program that shouldn't have broken anything, in their opinion,
        but which actually {hosed} the code completely.
     
        [{Jargon File}]