Inconsistent return value in FanoutCache when requesting expire_time

[sevdog]

When using FanoutCache.get if a timeout or a sqlite error occurs it only returns the provided default which is inconsistent with the documented behaviour when providing expire_time=True:

if True, return expire_time in tuple

This may lead to unexcpeted errors like "cannot unpack non-iterable NoneType object". The problem is that the expire_time parameter is only handled in ther underlaying cache and not in the except branch.

python-diskcache/diskcache/fanout.py

Lines 257 to 287 in ebfa37c

	def get(
	self,
	key,
	default=None,
	read=False,
	expire_time=False,
	tag=False,
	retry=False,
	):
	"""Retrieve value from cache. If `key` is missing, return `default`.
	If database timeout occurs then returns `default` unless `retry` is set
	to `True` (default `False`).
	:param key: key for item
	:param default: return value if key is missing (default None)
	:param bool read: if True, return file handle to value
	(default False)
	:param float expire_time: if True, return expire_time in tuple
	(default False)
	:param tag: if True, return tag in tuple (default False)
	:param bool retry: retry if database timeout occurs (default False)
	:return: value for item if key is found else default
	"""
	index = self._hash(key) % self._count
	shard = self._shards[index]
	try:
	return shard.get(key, default, read, expire_time, tag, retry)
	except (Timeout, sqlite3.OperationalError):
	return default