only in patch2:
unchanged:
--- a/core/tests/Drupal/Tests/Core/UnroutedUrlTest.php
+++ b/core/tests/Drupal/Tests/Core/UnroutedUrlTest.php
@@ -114,7 +114,6 @@ public function providerFromInvalidUri() {
       // Schemeless paths.
       ['test'],
       ['/test'],
-      ['//test'],
       // Schemeless path with a query string.
       ['foo?bar'],
       // Only a query string.