Cannot open server socket: Address already in use

[nponeccop]

CPAN Testers for 2.19 show a reincarnation of #50 on MacOSX:

• 5.27.9 Mac OS X
• 5.26.0 Mac OS X

[nponeccop]

CPAN Testers for 2.20 show a failure on Dragonfly BSD:

• FAIL Test-TCP-2.20 5.26.3 Dragonfly BSD

[nponeccop]

CPAN Testers for 2.22 show a failure on NetBSD. However, it's IPv6-specific:

• FAIL Test-TCP-2.22 5.20.0 NetBSD

   # found an empty IPv6 port

    #   Failed test 'port 49169 on ::1 is closed'
    #   at t/11_net_empty_port.t line 13.
    # Looks like you failed 1 test of 2.

#   Failed test 'v6'
#   at t/11_net_empty_port.t line 51.
Couldn't create socket: Address already in use at t/11_net_empty_port.t line 16.
# Tests were run but no plan was declared and done_testing() was not seen.
# Looks like your test exited with 2 just after 3.
t/11_net_empty_port.t .......... 
Dubious, test returned 2 (wstat 512, 0x200)