test: ConnectionRefusedError on consecutive runs the same test

[hebasto]

On Ubuntu Focal running the same test some times in a row

$ BITCOIND=/home/hebasto/bitcoin/src/qt/bitcoin-qt QT_QPA_PLATFORM=minimal ./test/functional/feature_versionbits_warning.py

I eventually got

AssertionError: [node 0] Node returned non-zero exit code (-11) when stopping
...
ConnectionRefusedError: [Errno 111] Connection refused
[node 0] Cleaning up leftover process

[maflcko]

Related, but different: #18623

[willcl-ark]

I have just tried to reproduce this on 21.04 but have been unable to do so. QT_QPA_PLATFORM=minimal did not work on my system (plugin could not load application fonts) so I tested with QT_QPA_PLATFORM=offscreen, running the test 20 times:

will@ubuntu in bitcoin (032ceb1 🏷  v24.0rc2) [?] via 🐍 v3.6.12
❯ for i in (seq 1 20)
      BITCOIND=/home/will/src/bitcoin/src/qt/bitcoin-qt QT_QPA_PLATFORM=offscreen ./test/functional/feature_versionbits_warning.py
  end

It seems unlikely that this is related to the QPA platform, but do you think it's worth testing on a 20.04 VM too?

[hebasto]

It seems unlikely that this is related to the QPA platform

Agree.

but do you think it's worth testing on a 20.04 VM too?

It won't hurt :)

[maflcko]

Can this be closed, given that the bug is fixed in recent version of Ubuntu?

[fanquake]

I think so. Is this even a bug in Bitcoin Core?