Attempt using selected DB as authSource

For BC, this attempt is only made when both connection attempts failed
using regular options. An extra attempt shouldn't be made if authSource
is explicit.

adminer/drivers/mongo.inc.php

@@ -643,6 +643,11 @@ function connect() {
 		if (($auth_source = getenv("MONGO_AUTH_SOURCE"))) {
 			$options["authSource"] = $auth_source;
 		}
+
+		return connect_with_retries($connection, $server, $options);
+	}
+
+	function connect_with_retries($connection, $server, $options) {
 		try {
 			$connection->_link = $connection->connect("mongodb+srv://$server", $options);
 			return $connection;
@@ -651,10 +656,14 @@ function connect() {
 				$connection->_link = $connection->connect("mongodb://$server", $options);
 				return $connection;
 			} catch (Exception $ex) {
-				return $ex->getMessage();
+				if ($options["authSource"] == "") {
+					$options["authSource"] = $options["db"];
+					return connect_with_retries($connection, $server, $options);
+				} else {
+					return $ex->getMessage();
+				}
 			}
 		}
-		return $connection;
 	}
 
 	function alter_indexes($table, $alter) {