[DRE-maint] Bug#1072535: puma: FTBFS randomly: test failures

[Lucas Nussbaum]

Hi Santiago,

I built a local version of the Debian package based on the upstream
'master' branch (including commit 231555c3), and ran some tests in
virtual machines with 1 or 2 CPUs.

With 1 CPU, I encountered hangs with the following test:
TestIntegrationSingle#test_term_suppress

And also the following test failed:
TestIntegrationSingle#test_int_refuse = TestIntegrationSingle#test_int_refuse = TestIntegrationSingle#test_int_refuse = /root/puma.git/lib/puma/single.rb:63:in `join': No live threads left. Deadlock? (fatal)
2 threads, 2 sleeps current:0x000055f1096a60f0 main thread:0x000055f1096a60f0
* #<Thread:0x00007fb0699ea9a0 sleep_forever>
   rb_thread_t:0x000055f1096a60f0 native:0x00007fb083a74740 int:0
   
* #<Thread:0x00007fb067a58178 at puma srv /root/puma.git/lib/puma/server.rb:269 sleep_forever>
   rb_thread_t:0x000055f109d04e60 native:0x00007fb06675b6c0 int:0
    depended by: tb_thread_id:0x000055f1096a60f0

With 2 CPUs, I ran into some tests failures, but maybe I need to check
with more RAM.

So we are not quite there yet...


my incant.yaml for reference:
```
instances:
  n1: &n
    image: images:debian/13
    provision: |
      #!/bin/bash
      set -xe
      apt-get update
      echo deb-src http://deb.debian.org/debian trixie main contrib > /etc/apt/sources.list.d/trixie-src.list
      apt-get update
      apt-get -y build-dep puma
      apt-get -y install ruby-bundler git git-buildpackage quilt
      git config --global --add safe.directory /incant/puma
      cat <<-EOS > /etc/security/limits.conf
      * soft nofile 65535
      * hard nofile 65535
      root soft nofile 65535
      root hard nofile 65535
      EOS
    vm: true
    type: c1-m4
  n2:
    <<: *n
    type: c2-m4
```

Lucas