Multiple response URLs not working correctly

The fix for #161 breaks multi-URL functionality.

Test case:

def test_multiple_urls():
    @responses.activate
    def run():
        responses.add(responses.GET, 'http://example.com/one', body='one')
        responses.add(responses.GET, 'http://example.com/two', body='two')

        resp = requests.get('http://example.com/two')
        assert_response(resp, 'two')
        resp = requests.get('http://example.com/one')
        assert_response(resp, 'one')

    run()
    assert_reset()

[beliaev-maksim]

@markstory test from the issue is present in current unit tests and passes OK, please close

[ngaya-ll]

This is behaving as expected per https://github.com/getsentry/responses/pull/171 (see this comment).

• Initially there is just one response registered.
• When the first request is made, the first response is returned.
• When the second response is created, it is appended to the list of responses.
• When the second request is made, the first response is returned again. At this point the first response is discarded since there are multiple matches.
• Subsequent requests will return the second response.