Ajax + jQuery + 302 = Weird behavior

gistfile1.js

$.ajax({
    type: 'POST',
    url: url,
    data: $('form').serialize(),
    success: function(a) { 
        console.log("success",a); 
    } ,
    statusCode: { 
        200: function(a) { 
            console.log("200",a); 
        },
        400: function(a) { 
            console.log("400",a); 
        },
        404: function(a) { 
            console.log("404",a); 
        },
        500: function(a) { 
            console.log("500",a); 
        },
    },
    error:function(a) { 
        console.log("error",a); 
    },
    complete: function(a) { 
        console.log("complete",a); 
    }
});


//output
/*
Como é:
    200, Object
    error, Object
    complete, Object
Como deveria ser:
    success, Object
    complete, Object7
*/