Backport #9301 "Users running into timeouts with error messages that are unhelpful" to 3.14.z
See attached bugzilla.
There was some additional discussion with a separate upstream user, who was running into this same issue: https://riot.im/app/#/room/#pulp:matrix.org/$xyV5D40cKUjqOYK7n7fk3J8v1RAqsu1KfafcYl968v8
The user had hypothesized that that maybe the "retries" were all counting towards the same "total timeout", but we have no confirmation of this.
This upstream aiohttp issue includes the same traceback and might provide some insight: https://github.com/aio-libs/aiohttp/issues/5239#issuecomment-727544671
I did also notice that we use the same ClientSession for all of a downloader's requests, that might be relevant: https://github.com/pulp/pulpcore/blob/master/pulpcore/download/http.py#L161-L163