Passing a command as string when creating a "Symfony\Component\Process\Process" instance is deprecated since Symfony 4.2, pass it as an array of its arguments instead, or use the "Process::fromShellCommandline()" constructor if you need features provided

Let's use same way, this is only file which using command line as not array

This test should gone, but it takes time, so still make sense to fix

To make run this test locally I got notice which blocks this test probably it's separate issue but with this patch I can pass this test lcoally

web $ php core/scripts/test-site.php install --json --langcode fr --setup-file core/tests/Drupal/TestSite/TestSiteMultilingualInstallTestScript.php --db-u
rl "$SIMPLETEST_DB"
#0  drupal_requirements_severity() called at [/var/www/html/web/core/includes/install.core.inc:2266]
#1  install_display_requirements() called at [/var/www/html/web/core/includes/install.core.inc:1403]
#2  install_download_translation() called at [/var/www/html/web/core/includes/install.core.inc:693]
#3  install_run_task() called at [/var/www/html/web/core/includes/install.core.inc:568]
#4  install_run_tasks() called at [/var/www/html/web/core/includes/install.core.inc:118]
#5  install_drupal() called at [/var/www/html/web/core/lib/Drupal/Core/Test/FunctionalTestSetupTrait.php:286]
#6  Drupal\TestSite\Commands\TestSiteInstallCommand->doInstall() called at [/var/www/html/web/core/tests/Drupal/TestSite/Commands/TestSiteInstallCommand.php:199]
#7  Drupal\TestSite\Commands\TestSiteInstallCommand->installDrupal() called at [/var/www/html/web/core/tests/Drupal/TestSite/Commands/TestSiteInstallCommand.php:189]
#8  Drupal\TestSite\Commands\TestSiteInstallCommand->setup() called at [/var/www/html/web/core/tests/Drupal/TestSite/Commands/TestSiteInstallCommand.php:99]
#9  Drupal\TestSite\Commands\TestSiteInstallCommand->execute() called at [/var/www/html/web/vendor/symfony/console/Command/Command.php:255]
#10 Symfony\Component\Console\Command\Command->run() called at [/var/www/html/web/vendor/symfony/console/Application.php:1000]
#11 Symfony\Component\Console\Application->doRunCommand() called at [/var/www/html/web/vendor/symfony/console/Application.php:271]
#12 Symfony\Component\Console\Application->doRun() called at [/var/www/html/web/vendor/symfony/console/Application.php:147]
#13 Symfony\Component\Console\Application->run() called at [/var/www/html/web/core/scripts/test-site.php:24]
/var/www/html/web $ php core/scripts/test-site.php install --json --langcode fr --setup-file core/tests/Drupal/TestSite/TestSiteMultilingualInstallTestScript.php --db-u
rl "$SIMPLETEST_DB"
{"db_prefix":"test63975176","user_agent":"simpletest63975176:1600816140:5f6a840c624f55.44641538:pzQEd6FuyQVYRCirQbfFB5sCEUYr4hk7U5UxcuuUBoM","site_path":"sites\/simpletest\/63975176"}

I think better to remove hunk from #7 as this fix out of scope and possibly to reproduce only manually, because ci runs tests only once

+++ b/core/includes/install.core.inc
@@ -1400,7 +1400,8 @@ function install_download_translation(&$install_state) {
+  // Skip when NULL or [] as it means translations ready.
+  if ($requirements && $output = install_display_requirements($install_state, $requirements)) {

I don't know what "as it means translations ready" means? I think this needs a wording cleanup if it stays.

It's from install_check_translations() function, it may return NULL or empty array but later functions expects array

Maybe that's better wording for comment

Or kinda it

I think the change in #13 sounds ok.

Looks like a simple change.

The comment in #13 looks fine to me too.

Committed 2958021 and pushed to 9.1.x. Thanks!

@catch push went wrong?