Recover installation when creating the user failed

Signed-off-by: Joas Schilling <coding@schilljs.com>

Author: nickvergessen

lib/private/Setup/MySQL.php

@@ -129,6 +129,7 @@ private function createDBUser($connection) {
 				'exception' => $ex,
 				'app' => 'mysql.setup',
 			]);
+			throw $ex;
 		}
 	}
 
@@ -137,6 +138,9 @@ private function createDBUser($connection) {
 	 * @param IDBConnection $connection
 	 */
 	private function createSpecificUser($username, $connection): void {
+		$rootUser = $this->dbUser;
+		$rootPassword = $this->dbPassword;
+
 		try {
 			//user already specified in config
 			$oldUser = $this->config->getValue('dbuser', false);
@@ -179,6 +183,9 @@ private function createSpecificUser($username, $connection): void {
 				'exception' => $ex,
 				'app' => 'mysql.setup',
 			]);
+			// Restore the original credentials
+			$this->dbUser = $rootUser;
+			$this->dbPassword = $rootPassword;
 		}
 
 		$this->config->setValues([