pivoter fields are wiped by options()

[Guibod]

I've stumble on this annoying bug here on python 3.4.

import unittest
from scorched.search import SolrSearch

class TestOptionsMethodWipesPivots(unittest.TestCase):
    def test_there_is_a_problem_with_pivot_by_with_facet(self):
        facet = 'facet'
        pivot = 'pivot'

        search = SolrSearch(None)
        search = search.facet_by(facet, mincount=1).pivot_by([pivot, facet], mincount=1)
        self.assertIn(pivot, search.pivoter.fields)
        self.assertEqual(search.pivoter.fields[pivot], {'mincount': 1})
        self.assertIn(facet, search.pivoter.fields)
        self.assertEqual(search.pivoter.fields[facet], {'mincount': 1})

        options = search.options()
        self.assertIn('facet.pivot', options)
        self.assertEqual(options['facet.pivot'], 'facet,pivot')

        self.assertIn(pivot, search.pivoter.fields)
        # Equals True
        self.assertEqual(search.pivoter.fields[pivot], {'mincount': 1})
        self.assertIn(facet, search.pivoter.fields)
        self.assertEqual(search.pivoter.fields[facet], {'mincount': 1})

    def test_there_is_a_problem_with_pivot_by_even_without_facet(self):
        facet = 'facet'
        pivot = 'pivot'

        search = SolrSearch(None)
        search = search.pivot_by([pivot, facet], mincount=1)
        self.assertIn(pivot, search.pivoter.fields)
        self.assertEqual(search.pivoter.fields[pivot], {'mincount': 1})
        self.assertIn(facet, search.pivoter.fields)
        self.assertEqual(search.pivoter.fields[facet], {'mincount': 1})

        options = search.options()
        self.assertIn('facet.pivot', options)
        self.assertEqual(options['facet.pivot'], 'facet,pivot')

        # Equals True
        self.assertIn(pivot, search.pivoter.fields)
        self.assertEqual(search.pivoter.fields[pivot], {'mincount': 1})
        self.assertIn(facet, search.pivoter.fields)
        self.assertEqual(search.pivoter.fields[facet], {'mincount': 1})