read buffer tests on FreeBSD are bailing out sporadically

Describe the bug

Every once in a while, read buffer tests on FreeBSD are bailing out sporadically, like in this CPAN Testers report.

See #954 also, which is similar, or it's still the same even.

These two test results seems to be generated on the same testing box (same deps, rex version, perl version, OS version, architecture, uname output, etc.):

• FAIL
• PASS

How to reproduce it

Since it seems sporadic, I'm not exactly sure about reproduction and we would probably need help from FreeBSD users.

Steps to reproduce the behavior:

1. run t/read_buffers.t tests (probably many times until it happens)

Shortest code example that demonstrates the bug:

$ prove -l t/read_buffers.t

or perhaps

$ perl t/read_buffers.t

Expected behavior

t/read_buffers.t test should reliably finish successfully on FreeBSD systems.

Circumstances

• Rex version: 1.10.0 (probably older ones too)
• Perl version: 5.30.2 (probably older ones too)
• OS running rex: FreeBSD 13.0 (probably older ones too)
• OS managed by rex: -

Debug log

Not a debug log, but test fails with:

Bailout called.  Further testing stopped:  Reading from buffer timed out
FAILED--Further testing stopped: Reading from buffer timed out
*** Error code 255

Start with t/read_buffers.t and run it repeatedly using prove -l t/read_buffers.t or perl t/read_buffers.t on FreeBSD. Compare the sporadic timeout with the linked CPAN Tester reports and issue #954; done means the test reliably finishes successfully on FreeBSD systems.