get_many doesn't work with several backends about cashews

[AIGeneratedUsername]

There are two problems here.

The first problem is that get_many returns something wrong when we use Memory backend (but Redis backend works fine):

If this is not a bug, but a feature, then please explain me.

import asyncio
from cashews import cache


async def func():
    cache.setup('mem://', prefix='foobar')

    print(await cache.set('foobar:123', 'value_1', expire=10_000))
    print(await cache.set('spameggs:123', 'value_2', expire=10_000))

    print(await cache.get_many('foobar:123', 'spameggs:123', 'foobar:123'))    # ('value_1', None, 'value_1')
    print(await cache.get_many('spameggs:123', 'foobar:123', 'spameggs:123'))  # ('value_2', None, 'value_2')


asyncio.run(func())

Another problem is that using prefix like "mem" for Redis backend gives a side effect that I can not explain now

import asyncio
from cashews import cache


async def func():
    cache.setup('redis://0.0.0.0', prefix='mem')

    print(await cache.set('mem:123', 'value_1', expire=1_000))
    print(await cache.set('mem:456', 'value_2', expire=1_000))

    print(await cache.get_many('mem:123', 'mem:456', 'mem:123'))  # (None, None, None)
    print(await cache.get_many('mem:456', 'mem:123', 'mem:456'))  # (None, None, None)


asyncio.run(func())

Using any other prefix makes get_many to be working.

---

Let's wait for Krukov's help here. I never reviewed/investigated "cashews/wrapper.py" code.

[Krukov]

Hello,
yes first issue that @easysugar mentioned is a bug and it is a part of wrapper. I think I can fix it a little bit latter.

The second one is not depends on prefix and the bug is much more serious. That is bug because of _ in value (value_1)
I added more details in separate issue

[Krukov]

So the second bug fixed #74

[Krukov]

Fixed with 4.5.0