network-no-diff test is broken for both 1.4.0 regression build and head build

While upgrading protobuf to 27.2, I am seeing some regression test failure for network-no-diff.test

ERROR: network-no-diff
======================

%begin 1719699304 265 0
%end 1719699304 265 0
%window-add @0
%sessions-changed
%session-changed $0 0
%window-renamed @0 bash
%sessions-changed
%exit
Running server test baseline.
select() with zero timeout called too often on server during baseline
travis_fold:start:network-no-diff.test-baseline.tmux.log
%begin 1719699304 265 0
%end 1719699304 265 0
%window-add @0
%sessions-changed
%session-changed $0 0
%window-renamed @0 bash
%output %0 \015\015\012\015\012
%output %0 \033[?1049h\033[?1h\033[?5l\033[r\033[0m\033[H\033[2J\033[?25l\033[K\012\033[K\012\033[K\012\033[K\012\033[K\012\033[K\012\033[K\012\033[K\012\033[K\012\033[K\012\033[K\012\033[K\012\033[K\012\033[K\012\033[K\012\033[K\012\033[K\012\033[K\012\033[K\012\033[K\012\033[K\012\033[K\012\033[K\012\033[K\033[1;1H\033[?25h\033[0m\033[?2004l\033[?1003l\033[?1002l\033[?1001l\033[?1000l\033[?1004l\033[?1015l\033[?1006l\033[?1005l
%output %0 \033[?25l\012x\015\033[?25h
%window-renamed @0 perl5.30
%output %0 @@@ server complete @@@
%paste-buffer-changed buffer0
%output %0 @@@ runtime   0:00.07 @@@\015\012
%output %0 \033[?1l\033[0m\033[?25h\033[?1003l\033[?1002l\033[?1001l\033[?1000l\033[?1015l\033[?1006l\033[?1005l\033[?1049l
%output %0 [mosh is exiting.]\015\012
%output %0 @@@ exitstatus: 0 @@@\015\012
%sessions-changed
%exit
travis_fold:end:network-no-diff.test-baseline.tmux.log
ERROR network-no-diff.test (exit status: 99)

Start by running network-no-diff.test against the 1.4.0 regression build and the head build, then compare the baseline tmux log output and the select() timeout failure. Trace how the test's baseline is generated and identify the difference associated with protobuf 27.2; done means the test passes for both builds without the reported error.