allow umlauts in logins

core/Piwik.php

@@ -589,7 +589,7 @@ class Piwik
         $l = strlen($userLogin);
         if (!($l >= $loginMinimumLength
             && $l <= $loginMaximumLength
-            && (preg_match('/^[A-Za-z0-9_.@+-]*$/D', $userLogin) > 0))
+            && (preg_match('/^[A-Za-zÄäÖöÜüß0-9_.@+-]*$/D', $userLogin) > 0))
         ) {
             throw new Exception(Piwik::translate('UsersManager_ExceptionInvalidLoginFormat', array($loginMinimumLength, $loginMaximumLength)));
         }

tests/PHPUnit/Integration/PiwikTest.php

@@ -125,6 +125,7 @@ class PiwikTest extends IntegrationTestCase
             'aa',
             'aaa',
             'aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa',
+            'äÄüÜöÖß',
             'shoot_puck@the-goal.com',
         );
         foreach ($valid as $key => $value) {