added test case to investigate KT-2495

libraries/stdlib/test/regressions/Kt2495Test.kt

@@ -0,0 +1,20 @@
+package regressions
+
+import kotlin.test.assertEquals
+import org.junit.Test as test
+
+fun f(xs: java.util.Iterator<Int>): Int {
+    var answer = 0
+    for (x in xs)  {
+        answer += x
+    }
+    return answer
+}
+
+class Kt2495Test {
+    test fun duplicateIteratorsBug() {
+        val list = arrayList(1, 2, 3)
+        val result = f(list.iterator()!!)
+        assertEquals(6, result)
+    }
+}