Bug#908942: libio-socket-ssl-perl: FTBFS: Connection refused at t/verify_fingerprint.t line 49 and tests hang

[Damyan Ivanov]

Package: src:libio-socket-ssl-perl
Version: 2.059-3
Severity: serious
Justification: fails to build from source (but built successfully in the past)

https://buildd.debian.org/status/fetch.php?pkg=libio-socket-ssl-perl&arch=all&ver=2.059-3&stamp=1537087640&raw=0

I am able to reproduce this if I run `prove -lb t/verify_fingerprint.t` several 
hundred times in a row, but I can't figure out what could be wrong.

Some times the test hangs, with parent calling wait(-1) and child doing 
accept(). Some times the test fails without hanging.

The test spawns two child processes, each one listening on a random port 
(chosen by the OS). The listen() call happens before the fork(), so it seems to 
me that a later connection attempt from the parent cannot fail.

The listen queue is set to 10, and each of the children is being connected less 
than 10 times.

The child processes are designed to exit when they are connected and 
disconnected without any data being sent. Perhaps this causes one of them to 
exit before the parent does its tests, but what other process makes that 
connection is a mistery.

I'll try adding some debugging output to the children and see if this "foreigh" 
connection attempt is the reason.


-- System Information:
Debian Release: buster/sid
  APT prefers unstable-debug
  APT policy: (500, 'unstable-debug'), (500, 'unstable'), (1, 'experimental')
Architecture: amd64 (x86_64)

Kernel: Linux 4.18.0-1-amd64 (SMP w/4 CPU cores)
Locale: clean
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled