fix scan iter command issued to different replicas

[agnesnatasya]

Pull Request check-list

• Do tests and lints pass with this change?
  • lint passes
  • test passes on Ubuntu 22.04, python3.11.2

Starting Redis tests
= 2352 passed, 1235 skipped, 849 deselected, 29 xpassed, 347 warnings in 163.65s (0:02:43) =
Waiting for 6 cluster nodes to become available
All nodes are available!
= 1571 passed, 1494 skipped, 1396 deselected, 4 xpassed, 244 warnings in 728.56s (0:12:08) =

• Do the CI tests pass with this change (enable it first in your forked repo and wait for the github action build to finish)? all succeeded in my fork.
• Is the new or changed code fully tested? added tests coverage
• Is a documentation update included (if this change modifies existing APIs, or introduces new ones)? bugfix only
  • I added some docstring to redis.asyncio.sentinel module. I wanted to check if the rST syntax is correct, but this module is not included in the builddir's index, so I think it's no-op.
• Is there an example added to the examples folder (if applicable)? bugfix only
• Was the change added to CHANGES file? bugfix only

fix scan iter command issued to different replicas

Fixes #3197. See linked issue for full description of the bug

[agnesnatasya]

Some of the CI tests fails flakily with a segmentation fault - if i rerun the CI in my fork, it would work most of the time. But I don't have permission to rerun it in the main repository.
Do you know whether this is expected? @gerzse
Thank you!!

[gerzse]

Thanks, this is a valid point. I left some comments in the changes, and I have one more general comment: the implementation covers now the async code. Did you leave out the sync code intentionally, or would it make sense to also adapt that one?

[gerzse]

What if there are many connections? This linear search might slow down things.

[gerzse]

Would it make sense to use a more general name, e.g. instead of request_id use context_id? Would it express better the fact that you are basically trying to run several commands in the same context?

[gerzse]

When would these entries be removed from the dict? So that it does not grow indefinitely.

[gerzse]

Some of the CI tests fails flakily with a segmentation fault - if i rerun the CI in my fork, it would work most of the time. But I don't have permission to rerun it in the main repository. Do you know whether this is expected? @gerzse Thank you!!

Those segmentation faults have been there for a long time, to be honest I have no idea why they happen. They are so annoying. Eventually I'll spend some time trying to dig deeper.