Issue #3437178 by immaculatexavier, quietone, smustgrave, alexpott: Simplify...

    // we're querying. Catch exceptions and report that the source database is

    // not Drupal.

    // Drupal 5/6/7 can be detected by the schema_version in the system table.

    $version_string = FALSE;

    if ($connection->schema()->tableExists('system')) {

      try {

        $legacy_version_string = $connection

        $version_string = $connection

          ->query('SELECT [schema_version] FROM {system} WHERE [name] = :module', [':module' => 'system'])

          ->fetchField();

        if ($legacy_version_string && $legacy_version_string[0] == '1') {

          if ((int) $legacy_version_string >= 1000) {

            $version_string = '5';

          }

        }

        else {

          $version_string = substr($legacy_version_string, 0, 1);

        }

      }

      catch (DatabaseExceptionWrapper $e) {

        // All database errors return FALSE.

      }

    }

    return $version_string;

    return match (TRUE) {

      !isset($version_string) => FALSE,

      (int) $version_string >= 6000 => substr($version_string, 0, 1),

      (int) $version_string >= 1000 => '5',

      default => FALSE,

    };

  }

  /**