Debian/RPM package launcher should honor WP_CLI_PHP and WP_CLI_PHP_ARGS

[schlessera]

Problem

The Debian (and RPM) packages ship the raw Phar as the executable:

# utils/wp-cli-updatedeb.sh
mv ../wp-cli.phar usr/bin/wp
chmod +x usr/bin/wp

So /usr/bin/wp is the Phar itself and launches via its #!/usr/bin/env php shebang, i.e. the first php on PATH. Neither WP_CLI_PHP nor WP_CLI_PHP_ARGS is ever read, because the shell wrapper that reads them (bin/wp in wp-cli/wp-cli) is not part of a Phar install. Reported downstream in wp-cli/wp-cli#5886.

This has always been the case (verified against the 2.5.0, 2.9.0 and 2.11.0 .deb artifacts, all of which install a Phar whose first line is #!/usr/bin/env php). It is not a regression from wp-cli/wp-cli#5672, which only corrected what wp cli info reports.

Proposed fix

Stop shipping the bare Phar as /usr/bin/wp. Instead:

• Install the Phar at a stable path, e.g. /usr/share/wp-cli/wp-cli.phar.
• Install a launcher at /usr/bin/wp implementing the existing bin/wp semantics:

#!/usr/bin/env sh
php="${WP_CLI_PHP:-$(command -v php)}"
export WP_CLI_PHP_USED="$php"
exec "$php" $WP_CLI_PHP_ARGS /usr/share/wp-cli/wp-cli.phar "$@"

This makes WP_CLI_PHP select the interpreter, lets WP_CLI_PHP_ARGS pass -c / -n / -d before the Phar, and makes the php.ini used line in wp cli info correct automatically (the chosen interpreter loads its own config). No change to core get_php_binary() and no reversal of wp-cli/wp-cli#5672 is required.

Compatibility notes (why 3.0.0)

The package layout changes: /usr/bin/wp stops being the Phar. Needs review of:

• wp cli update / self-update behavior against a launcher + separate Phar path.
• Phar-path reporting in wp cli info.
• Upgrades from older packages that shipped the Phar directly at /usr/bin/wp.
• Packaging tests and the md5sums / man-page generation steps in the build script.
• Applying the same change to the RPM build.

Acceptance

• Default invocation (no vars) still uses PATH php.
• WP_CLI_PHP=/usr/bin/php8.1 wp cli info reports and runs under that binary.
• WP_CLI_PHP_ARGS="-n" and WP_CLI_PHP_ARGS="-c /path/php.ini" take effect.
• Clean upgrade from a pre-launcher package.