Is it possible to update the multi-warehouse support module (as of yesterday packaged with Magento 2.3) if you already have Magento 2.3 installed from before MSI 1.1 was included (in particular with Magento having been installed via GUI and not composer)?
Assuming i need to re-install. I figured i should do it with composer this time. On my shared hosting i installed composer to ~/bin/composer.phar. I changed the header from #!/usr/bin/env php to #!/usr/local/bin/php72 -c /home/user/public_html/shop/php.ini but composer is throwing the error Fatal Error: Uncaught PharException: phar "/home/user/bin/composer.phar" has a broken signature in /home/user/bin/composer.phar:23, which has "Phar::mapPhar('composer.phar')