Add reference to fix for pipe i/o

Author: hoodmane

Lib/test/test_io.py

@@ -3933,6 +3933,7 @@ def test_issue35928(self):
         self.assertEqual(res + f.readline(), 'foo\nbar\n')
 
     @unittest.skipUnless(hasattr(os, "pipe"), "requires os.pipe()")
+    @unittest.skipIf(support.is_emscripten, "Would be fixed by emscripten-core/emscripten#23306")
     def test_read_non_blocking(self):
         import os
         r, w = os.pipe()