'Load a proxy from an app.conf to get the memcache_ring
:returns: the memcache_ring of the memcache middleware filter'

@patch_policies
def _loadapp(self, proxy_config_path):

    with mock.patch('swift.proxy.server.Ring'):
        app = loadapp(proxy_config_path)
    memcache_ring = None
    while True:
        memcache_ring = getattr(app, 'memcache', None)
        if memcache_ring:
            break
        app = app.app
    return memcache_ring
