find_extra_block_dev piped find_extra_block_devs into head -1. Since
find_extra_block_devs prints every eligible disk and ends with echo
"$devs", head closes the pipe after the first line and the producer's
echo races into SIGPIPE (echo: write error: Broken pipe), failing the
command substitution under pipefail/errexit.
The race only fires reliably now that the runners present two data disks
(sdb and sdc), so find_extra_block_devs emits multiple lines; with a
single disk the one-line output almost never triggered it.
Read the producer to completion with mapfile via process substitution
and return the first element, mirroring find_second_block_dev, so there
is no downstream head to close the pipe early.
Signed-off-by: Joshua Hoblitt <josh@hoblitt.com>
(cherry picked from commit 7079c9bf62)
Joshua Hoblitt
47f91adcb6