Refactor session db logging and key generation for sessions/otks While I was working on the redis sessiondb stuff, I noticed that log_wanrning, get_logger ... was duplicated. Also there was code to generate a unique key for otks that was duplicated. Changes: creating new sessions_common.py and SessionsCommon class to provide methods: log_warning, log_info, log_debug, get_logger, getUniqueKey getUniqueKey method is closer to the method used to make session keys in client.py. sessions_common.py now report when random_.py chooses a weak random number generator. Removed same from rest.py. get_logger reconciles all logging under roundup.hyperdb.backends.<name of BasicDatabase class> some backends used to log to root logger. have BasicDatabase in other sessions_*.py modules inherit from SessionCommon. change logging to use log_* methods. In addition: remove unused imports reported by flake8 and other formatting changes modify actions.py, rest.py, templating.py to use getUniqueKey method. add tests for new methods test_redis_session.py swap out ModuleNotFoundError for ImportError to prevent crash in python2 when redis is not present. allow injection of username:password or just password into redis connection URL. set pytest_redis_pw envirnment variable to password or user:password when running test.

import operator

class MultiMapping:
    def __init__(self, *stores):
        self.stores = list(stores)
    def __getitem__(self, key):
        for store in self.stores:
            if key in store:
                return store[key]
        raise KeyError(key)
    _marker = []
    def get(self, key, default=_marker):
        for store in self.stores:
            if key in store:
                return store[key]
        if default is self._marker:
            raise KeyError(key)
        return default
    def __len__(self):
        return sum([len(x) for x in self.stores])
    def push(self, store):
        self.stores.append(store)
    def pop(self):
        return self.stores.pop()
    def items(self):
        l = []
        for store in self.stores:
            l = l + list(store.items())
        return l