array values aren't formatted right

[drewp]

Passing tags=['a','b'] needs to make output like tags[]=a&tags[]=b

Use something like this:

        arrayedParams = []
        for k,v in params.items():
            if isinstance(v, list):
                arrayedParams.extend([(k+"[]", elem) for elem in v])
            else:
                arrayedParams.append((k, v))
...
            url = ... % (..., urlencode(arrayedParams))