apt-cache madison | grep -q and apt-cache policy | awk '...exit' can SIGPIPE
the writer under pipefail and report lsphp missing when it is there. Read
each output into a variable and match in the shell. Fixes the Shell-Checks
failure on trunk (lsphp-info-probe.test.sh structural scan).
Tested: lsphp-info-probe.test.sh 36/36, shellcheck clean, and the script run
in litespeedtech/openlitespeed:1.8.4-lsphp85 upgrades 8.5.0 -> 8.5.11 OK.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>