Merge pull request #5709 from dotty-staging/fix-#5218

Fix #5218: Add regression test

Author: Aggelos Biboudis

compiler/test-resources/repl/i5218

@@ -0,0 +1,7 @@
+scala> val tuple = (1, "2", 3L)
+val tuple: (Int, String, Long) = (1,2,3)
+scala> 0.0 *: tuple
+val res0: Double *: (Int, String, Long)(tuple) = (0.0,1,2,3)
+scala> tuple ++ tuple
+val res1: Int *: String *: Long *:
+  scala.Tuple.Concat[Unit, (Int, String, Long)(tuple)] = (1,2,3,1,2,3)