python-asyncio: update retry factors for actual exponential retries

[imrehg]

As per the aiohttp-retry library's code¹, the timeout is

timeout = self._start_timeout * (self._factor ** attempt)

This means the previous setting with "start_timeout=0.0" would have always just retried right away (0 timeout) regardless of the "factor" value, and also, "factor=0.0" would never have increased the timeout, rather it would have resulted in a 0 timeout regardless of the value of "start_timeout".

This double-zeroing effectively rendered exponential backoff to nothing (or rather "retries" number of retries in quick succession).

The update is a quick fix to set the same default as in aiohttp-retry. In the future this should likely be configurable (through extra Configuration settings perhaps?), as not all APIs are created equal, but this works as a quick fix for making retries more effective.

Connects to #17011

CC: @cbornet @tomplus @krjakbrjak @fa0311 @multani

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Footnotes

1. https://github.com/inyutin/aiohttp_retry/blob/ba2169891f5b32a5c59e48ca185dd8e68e44ded7/aiohttp_retry/retry_options.py#L38-L65 ↩

[wing328]

lgtm. thanks for the fix