Added test for KT-5272 which is not reproduced

idea/testData/completion/handlers/TypeArgOfSuper.kt

@@ -0,0 +1,13 @@
+trait X {
+    open fun fn() {}
+}
+
+open class Y {
+    public open fun fn() {}
+}
+
+class Z : Y(), X {
+    override fun fn() {
+        super<<caret>>.fn()
+    }
+}

idea/testData/completion/handlers/TypeArgOfSuper.kt.after

@@ -0,0 +1,13 @@
+trait X {
+    open fun fn() {}
+}
+
+open class Y {
+    public open fun fn() {}
+}
+
+class Z : Y(), X {
+    override fun fn() {
+        super<X<caret>>.fn()
+    }
+}

idea/tests/org/jetbrains/jet/completion/handlers/BasicCompletionHandlerTest.kt

@@ -142,4 +142,6 @@ public class BasicCompletionHandlerTest : CompletionHandlerTestBase(){
 
     fun testLocalClassCompletion() = doTest(1, "LocalClass", null, '\n')
     fun testNestedLocalClassCompletion() = doTest(1, "Nested", null, '\n')
+
+    fun testTypeArgOfSuper() = doTest(1, "X", null, '\n')
 }