code: def rename(self, core, other):
          
          params = {
              'action': 'RENAME',
              'core': core,
              'other': other,
          }
          return self._get_url(self.url, params=params)
docs: http://wiki.apache.org/solr/CoreAdmin#head-9473bee1abed39e8583ba45ef993bebb468e3afe