Investigate "Less than 1 bytes/sec transferred" errors

[lazka]

I've seen them with:

• repo.msys.org (locally)
• mirror2.sandyriver.net (in CI)

These are 2 out of 3 mirrors supporting http2, so maybe it is http2 related.
It can be reproduced by downloading multiple large files in parallel, though it's hit and miss.

Disabling the timeout doesn't help, it just makes everything grind to a halt here and never continues instead of showing the "Less than" error.

If it is indeed http2 related we could disable it in pacman.

[jeremyd2019]

I just saw

  error: failed retrieving file 'mingw-w64-i686-libwinpthread-git-10.0.0.r130.g13f9449c1-1-any.pkg.tar.zst.sig' from mirror.clarkson.edu : Operation too slow. Less than 1 bytes/sec transferred the last 10 seconds

on https://github.com/jeremyd2019/MINGW-packages/actions/runs/3452472922/jobs/5762399430
Is mirror.clarkson.edu the 3rd http2 mirror?

[lazka]

I was totally wrong, I forget that http2 is https only when I checked...

all our mirrors support http2, so this is not it...

[lazka]

I haven't seen those errors in a while. Maybe just luck though.

[cicku]

A random mirror operator here: I did some tests and tend to say something is not implemented correctly within pacman for parallel download. Based on the pcap on my server, the full file has been transmitted to the client, but pacman eventually returned error saying the speed is too slow.