Allow absent callbacks after partial ringback listener setup

tools/chatgui-android/router-tests/src/test/kotlin/com/utun/chat/data/AlertReleaseCleanupTest.kt

@@ -86,7 +86,7 @@ class AlertReleaseCleanupTest {
             CallRingback.startConnecting()
             val old = MediaPlayer.created.last()
             assertEquals(1, old.releaseCalls); assertFalse(old.released)
-            assertTrue(old.playbackError()); old.complete()
+            old.playbackError(); old.complete() // Ошибка регистрации listener могла произойти до его установки.
             assertEquals(1, old.releaseCalls)
             old.failures = emptySet(); CallRingback.stop()
             assertTrue(old.released); assertEquals(2, old.releaseCalls)